This week's weird fish is the Grunt sculpin, Rhamphocottus richardsonii â€“ a rather beautiful, almost dog-like, little marine fish that uses its fins to hop or walk along the seabed. Bob Mehen has the details â€“ and check out the video!
The more I look at weird fish, the less weird they look to me. I'm getting used to huge teeth, distended jaws, bulbous eyes, capacious stomachs and the many other bizarre features seen to such an extent that it now seems to me that a cod is a bigger ocean oddity than a Goblin shark.
However there are still many strange looking species waiting to surprise us with their perplexing piscine peculiarity, and Rhamphocottus richardsonii, commonly known as the Grunt sculpin, is one of them.
Monotypic families are often a rich hunting ground when it comes to strange and unusual fish species, so it's no surprise that the Grunt sculpin is the only member of the Rhamphocottidae – clearly taxonomists agree it's a bit different to other Scorpaeniformes.
Growing to little more than 10cm/4" they are odd, hunch-backed little fish, with over half their length made up by their armoured heads.
Their entire body is covered in multi-spined plates, the tips of which protrude through the skin, making this otherwise tempting morsel of a fish a prickly mouthful for potential predators.
Their common name comes from the grunting noise they emit when frightened or removed from the water which is itself another useful deterrent.
They are very poor swimmers, preferring to hop or walk along the sea bed with the aid of specially adapted thickened pectoral fin rays, but this lack of Michael Phelps like aquatic propulsion is explained when you see the sculpin at home. They spend much of their time within the empty shells of the Giant acorn barnacle, Balanus nubilus.
Inside these armoured retreats their odd shape makes far more sense, with their bony head filling the opening and making the dead barnacle look like all the other closed barnacles in the colony – and if the fish dives into its shelter head first, its tail is adapted to look like the feeding fans of a living barnacle.
These empty shells provide an excellent place for the fish to lay and guard its eggs.
Observations of the breeding behaviour of captive specimens report the pugnacious females chasing and holing up prospective partners when ready to breed. The female then guards the fertilised eggs until they hatch.
In the absence of barnacles they will set up home in anything from suitably sized shells to tin cans and bottles.
They typically live in the inter-tidal temperate waters of the North Pacific, but are found at greater depths of up to 200m in their most southerly range as they prefer cooler water. Their diet consists of small crustaceans, zooplankton and fish larvae.
This week's weird fish candidate certainly fits the bill, especially when the order they belong to is the Chimaeriformes, which basically translates as "monster shaped"....
Callorhinchus milii, more commonly known as the Plough-nosed chimaera or Ghost shark, is certainly an odd looking creature, as are all the Chimaera species which are thought to be among the oldest groups of fish living today, with an ancestry going back over 400 million years.
The origin of Callorinchus millii's common name is as plain as the nose on its face – the tip of its rostrum is extended into an odd, twisted club-like structure. Ironically given the etymology of its order's name the family's name "Callorhinchus" comes from the Greek for "beautiful snout". This peculiar proboscis is covered with sensory pores with which the fish can detect the weak electrical fields and movement of potential prey buried in the seabed as it roots around for a meal which typically consists of shellfish and small crustaceans which are crushed up by the fish's tooth plates.
They are a cartilaginous fish, related to sharks and to some extent share a similar body shape but with some clear differences. They have enlarged pectoral fins which they flap in a wing-like manner for swimming similar to rays in preference to using their tails.
The first of their two dorsal fins is home to a large venomous spine that can be used defensively. The chimaera's body is smooth and scale-less with a beautiful silvery white metallic background colouration, punctuated by dark blotches.
Its large, green eyes point to its natural habitat which is typically at depths of over 200m off the temperate coasts of Australia and New Zealand in the South-west Pacific.
They do however come into shallow water to breed with females laying large, flattened, leathery eggs onto the sea bed. These eggs harden and darken in colour as the embryo matures. The young eventually hatch out after about eight months of living on their yolk sack at around 15cm/6" long.
Adult Plough-nosed chimaeras can live to 15 years and grow to around 125cm/4'.
Despite being a popular food fish in fish and chip restaurants in Australia and New Zealand, their population remains stable and the species is not considered to be at risk.
Callorhinchus milii has recently been the subject of considerable scientific research with its genome being mapped. It has the smallest genome among known cartilaginous fish at about one third the size of the human genome. It is hoped this work will help further understanding of the evolution of vertebrates, as both humans and the chimaera share a common ancestor from 450 million years ago.
Tim Stoodley looks at the plight of the thousands of goldfish handed out as prizes at funfairs and carnivals every year, asks why the RSPCA is unable to prevent it happening and offers some possible solutions.
It's late April and the sunshine is beautiful. The conditions are perfect for a trip to Spalding's famous flower parade. We load the kids into the car and join the necessary queue of traffic heading towards one of the area's largest events. It's a picture perfect family day, we stumble around town and enjoy the festivities and then decide to end the day by visiting the fairground that is in town for the weekend.
Fantastic! A load of high, fast, noisy rides really get the adrenaline going. We've pumped the kids full of popcorn and candyfloss and spent far too much on rides nobody really enjoys!
So far the perfect day continues... wait! What's that? I swear that kid just walked past me with a goldfish in a bag! Must be this sunshine getting to me, or maybe I left my brains on the waltzer! Hold on, there is another one, and another, that one is being swung round in its little bag by a child no older than two, definitely not old enough to be transporting a fish. Why would people visit the fair on the way home from their local aquatics shop?
Ah, here's the problem, a coconut shy 'win a prize every time'. Hmm, seems fair for £5! Wait, the loser's prize is a goldfish! Oh my God! There are literally hundreds of the them in tiny little bags, not big enough for a sandwich. Hundreds of them. Hundreds of people also 'winning' them as they lose on the sure-to-be-fixed sideshow.
Oh look, you can buy a bowl for them... just £9.99! No sign of water conditioner or advice though.
Maybe the friendly looking stall worker will be able to offer some advice. I tell my other half to guard the kids while I pretend to know nothing about the goldfish I'm about to 'win'. Sure enough, I cannot hit the coconuts and get a goldfish rammed in my face – I didn't even get asked if I wanted it!
I asked the lady if I could I get some advice on them. 'Go to the library' is her response.
'How long will they live?' I enquire while she is trying to roll up more business. 'Few weeks normally' she snaps. So there I am, with a goldfish I have no home for, have no idea how to keep and what's more I still have nine more rides to go on.
Luckily, the little goldfish was quickly transported back to my fish house where it is now enjoying a 12' indoor pond. However, many more of his siblings wouldn't have been so lucky. Indeed, on my way out of the fair I noticed one dead goldfish on the floor – the bag had apparently been dropped and its contents sprawled on the footpath – and I also came across one dead, in its bag, in a dustbin.
Furthermore, I witnessed several goldfish being clung onto while their new owners enjoyed the big wheel, the waltzers and other fast rides certainly not suitable for a goldfish.
I came home feeling sick to the stomach. I was literally so angry that my partner quickly ushered the children off to the local park to prevent them from witnessing my outrage.
I am not naive, I knew full well that this particular fair, Roger Tuby and Sons, gave out goldfish as prizes. I knew this because I witnessed the same thing last year and the year before. However, naive or not, this cannot go on.
I've read today in a red-top newspaper that a man has been arrested for singing 'everybody was kung fu fighting' in front of an Asian couple. It is worth pointing out he was singing on stage to a large audience, not directly at the couple. How is it that we are policed to such an extent yet everybody stands by while these goldfish are given no option or hope of survival?
The problem isn't just found at the attitude of fair-going customers. Lots of families with young children still visit pet stores to buy a 'nemo' and stick it in a bowl. Unfortunately, only the most astute, moral-minded shops will refuse these sales. Literally thousands of fish are being given to people with no knowledge of how to keep them, or even a home for them in the first place. It's no wonder the fair workers believe they only live a few weeks.
The question I pose now is how is this different to me turning up at the busy flower parade and beating dogs to their death in front of happy, delightful customers? If I were to even attempt this I would be branded, quite rightly so, a monster. I'd no doubt end up in the paper and on the news as the ogre who mistreats animals.
I don't blame the carnival workers, they only supply the demand and most don't know better. I struggle not to but I don't really even blame the people who take them as prizes. They give in to the peer pressure of their children, which any parent will know is a daunting task.
Instead I blame two things: society as a whole who still, in this age, think it is OK to treat fish in general as second class citizens of the animal world.
Secondly, I blame the ministers who passed the Animal Welfare Act (2005). Originally this Act banned all animals as prizes. However, at the last moment it got amended to simply raise the age of winning a pet as a prize from 12 to 16 without parental consent. Without stereotyping, are a group of 16-year-olds responsible enough to win a goldfish at a fair? No. I can only imagine what fates some of those poor little fish, and indeed fish all over the world at carnivals and fairs, have suffered.
So, what's the answer I hear you ask? It's all good and well me ranting and raving at the people who actually care about these animals. You're the wrong people to preach to. However, I call upon you all to work together and bring what seems to be common sense in 2011 to the table. Would the trip to the fair be any less entertaining or exciting if fish weren't the prize? Of course not.
The instant reaction at this point for many people is to blame the authorities for letting this happen. It is worth pointing out though that the police and the RSPCA can only act on law. I had a chat with RSPCA Inspector Justin Stubbs to get a viewpoint from the people trying to help, but yet powerless to do anything.
Why can't the RSPCA stop fairs giving away fish as prizes?
"The Animal Welfare Act 2006 in England and Wales makes it an offence to give away an animal as a prize if the person can reasonably be believed to be under 16 and is not accompanied by an adult (there are some exceptions in sections 11(3)-(6) of the Act). This is not the case in Scotland, where under the Animal Health and Welfare (Scotland) Act 2006, it is an offence to offer or give an animal to another person as a prize (whatever their age), except where it is offered in a family context.
"This means we cannot prevent fish being given away as prizes, we can only stop under 16's from receiving them. Unfortunately, we cannot make laws, only help to enforce them."
What can the aquatics world do in the future to stop this practise occurring? How would we get this outlawed?
"Some councils license fairgrounds, and the things they can and can't do there. Changing the law under the current government to 'stop giving fish as prizes' realistically, won't happen. The RSPCA is opposed to giving any animal as a prize. Maybe lobbying individual councils into adding a caveat to their license, that no animals should be involved could work? If it was illegal to give fish away as prizes, it would be reasonable to expect the fairgrounds to start giving away other animals."
Why did the Animal Welfare Act get amended to exclude giving away fish as prizes?
"In the consultations, the RSPCA and other groups lobbied hard to have all animals as prizes stopped. It's not just fish that can be given away, pretty much any animal can be. Unfortunately, pressure from the fairground owners and other organisations prevailed and hence the only change was the change in age limit."
This goes to show that the one authority able to help has its hands tied by the laws they must enforce. It is the ministers who must act now and stop this barbaric practice. I see three possible solutions to this problem:
Firstly, we petition the government together to ban the transfer of ownership of a fish as a prize. However, as Mr. Stubbs from the RSPCA mentions above this would only pave the way for another animal to suffer a poor fate.
Secondly, we could possibly lobby local authorities to introduce a code of conduct within their licensing laws. Currently, any fair or carnival must be licensed by the local authority. Therefore, if the local council make it difficult for them obtain this license while giving away fish as prizes, then the fair owners are less likely to offer this attraction.
Thirdly, we could try to offer the carnival or fair owners the option of agreeing to a voluntary code of practice. This would include things such as offering advice with every fish, selling good sizes tanks at realistic prices and making sure the fish are appropriately housed while at the fair. Thereafter any fair or carnival failing to adhere to this code of conduct can be well published as a 'non-animal friendly fair' by us and fellow animal lovers, therefore damaging their reputation and credibility.
All three options are viable and will only serve towards helping these poor victims of the carnival industry. It can only be right that we act now and work towards a brighter future for these poor goldfish who have no hope or prospect.
We spend thousands of pounds a year on our beloved aquatic pets, normally just a handful of fish, now let's get together and save the thousands of goldfish who are unlucky enough to be shipped into this trade of terror.
Nathan Hill looks at the Coelacanth â€“ a non-extinct dinosaur that has lobes for fins and produces live young â€“ in the continuing weird fish series.
Many of us will already be familiar with this unusual fish, given its popularity in natural history documentaries. It is by no means the breakthrough discovery of the last decade or two that some believe it to be, although this has been the time when the majority of live specimens have been witnessed.
The fish was thought to have gone extinct about 65 million years ago, having first appeared at around an estimated 410 million years ago. Most of what was known about the group – all 80 or so species – had been methodically gathered from fossil evidence; a jaw here, a fin there.
The fish spectacularly reappeared when it was hauled upon the boat of Captain Hendrick Goosen on December 22nd, 1938. Museum official Marjorie Courtenay-Latimer was called in by local fisherman who were on standby to contact her in the event of discovering oddities, and she in turn had the fish preserved to the best of her abilities at the time and called in James Smith. Smith subsequently identified and named the discovery Latimeria chalumnae – a hybrid of a name, part in honour of a friend, and part in recognition of the region of the find.
There are now known to be two living Coelacanth species on this planet. L. chalumnae, and the more recently discovered L. menadoensis, which was found in an Indonesian marketplace. Formerly, Coelacanth had only been discovered along Western and Southern Africa, Madagascar, and the Comoro Islands, where L. chalumnae reside.
Coelacanths are hard to find in part because of their penchant for deeper waters. They normally live between 100 and 500m down, only venturing to shallower waters at night where they feed upon dozing fish.
The other reason they are tricky to find is that they like to reside in deep caves underwater, often sharing in surprisingly dense populations to one cave. They are a nervous fish, and many suspect that they are prey to sharks. Certainly, many sharks like to inhabit the same regions that Coelacanth do, and bodies have been discovered with bites taken out of them.
Coelacanth are big fish, often attaining over 1.5m. They have thick, toughened scales to protect them, and they are sluggish in a way that many fish that inhabit such cold, deep waters are.
Even so, they can be surprisingly mobile when they need to, and they certainly have the fins of a good swimmer. Many of their fins are paired, and they have twin pelvic and dorsal fins, as well as the two pectorals so familiar to modern fishes. Anyone who has seen footage of these fish moving can testify to their unusual and almost hypnotic rhythmic movements. Ingeniously, they will often use water flows and currents to move themselves around, literally hitching a ride on drifting water.
Often, the phrase ‘lobe finned’ is used to describe Coelacanth, without really explaining what this means. As well as having differences in the braincase and an ability to move their heads that most other fish lack, the phrase refers to the bone structure of the connection between fin and body. Where a modern, ray finned fish has several bones that connect to pelvic and pectoral regions, the coelacanth only has the one. Generally, their bones and muscles tend to be more developed in these regions, too.
These are ovoviviparous fish, meaning that they produce live offspring by having eggs that hatch and develop internally. A female may yield up to 26 of these pups at one time, but after that our knowledge of their reproduction is virtually nil. We know nothing of courtship, breeding, or even where the juveniles go to grow on.
This is a protected fish, although not a huge amount is known of actual wild populations. Many attempts at conservation have been started, some with greater success than others, and it certainly won’t be a specimen to turn up on the home aquarist’s radar any time soon. There is something to be said, however, in a fish that goes undetected for 65 million years, and then runs in to humans and trouble at the same time…
The video shows a Coelacanth caught in Sulawesi a few years back. Unfortunately the fish was doomed from the moment it reached the surface of the water. Given the temperature difference – some 20°F – between the water here and the water at the Coelacanth’s comfortable depths, it is generally accepted that even if the fish had been released from here it would have lacked the strength to fight its way back down to an acceptable level, through changes in its metabolism and oxygen requirements.
The Weedy sea dragon is a member of the Syngnathidae family, a group of that contains the seahorses and pipefish. We're all so familiar with seahorses that their weirdness has become almost unremarkable but this really is something wonderfully peculiar!
Let's face it, the seahorses are not really that similar to their equine namesakes are they? There's the distinct absence of hooves for a start, which isn't surprising given the lack of legs to put them on and I've yet to see a horse with a prehensile tail. Their common name's nod to nags is purely because of the shape of their heads, unless they have a love of sugar lumps I'm unaware of.
By contrast the Weedy sea dragon (Phyllopteryx taeniolatus) really does live up to its mythological moniker perhaps with the exception of fire breathing...
Check out the amazing video below:
Growing to around 45cm/18in, these marvellous mimics really do look like small dragons, complete with a set of wing like fins on their backs. Add to this their armoured body covered in bony plates, long tail and crested head and the sea dragon name really fits.
Their odd body shape is explained by their natural habitat. They are found along the temperate coast of South Australia in amongst kelp and other sea weeds and in these swaying algae forests they are especially cryptic as they hunt for their typical prey of mysids and other tiny marine crustaceans.
They lack a caudal fin and are poor swimmers, moving by the energetic fanning of their dorsal and pectorals. The fish pair up to breed in early summer, performing elaborate, synchronised swimming displays after which the female lays up to 250 eggs which are attached to the tail of the male.
The female plays no further part in the care of the eggs which the male now carries embedded in his tail for the next couple of months until they hatch into fully formed miniature versions of their parents.
There are unfortunately a number of threats to these fantastical fish, largely due to habitat damage. Commercial fishing of rock lobster has led to an increase in the population of the sea urchin species Centrostephanus rogersii on which the lobster preys. This urchin eats the seaweed and kelp that gives the sea dragons and their food shelter leaving them open to predation and starvation as well as an increased risk of being swept ashore during stormy weather.
Habitat degradation caused by human activity such as dredging, land reclamation, drainage run-off etc has also impacted on their distribution. These and other factors have led to Phyllopteryx taeniolatus being listed as 'Near threatened' on the IUCN red list.
Why not check out some of our other Weird fish of the week features? Barreleye
The amazing Goblin shark certainly lives up to the weird fish title. Just take a look at the video...
Sharks have been cruising the oceans for over 420 million years, which is ample time for evolution to throw up all manner of weirdness. The Goblin shark, Mitsukurina owstoni, is a case in point.
These poor fish have gained a reputation for ugliness which is not helped by the majority of images of them being taken post mortem with their impressive mouths extended.
This a little like judging a beauty contest, but only when the contestants are yawning... and dead.
In life the Goblin shark is a far more attractive creature. Their body shape is typical of what most of us would consider 'shark like', but with some marked differences.
The most obvious one is their rostrum (nose), which is greatly enlarged and flattened into a paddle shape. This is where they get their common name from as Japanese fishermen called them 'tenguzame' after 'tengu', a mythical goblin like creature from folklore with a long nose.
This impressive proboscis is covered in sensory pores known as 'the ampullae of Lorenzini' with which the shark can detect the electrical fields of prey both in the dark, and hidden in the seabed. This is where its most striking, but largely hidden adaptation comes into play.
The shark has a set of truly bizarre jaws which with the aid of special ligaments can project out in front of their resting position, rather like those on the creature in the film Alien.
These protractible jaws are filled with long slender teeth and can shoot out to snatch up any prey detected. Watch the video below to see those amazing jaws in action.
Unique amongst sharks, they have a generally pink colouration with just the oddly rounded fins carrying a blue-ish tint but this colouration fades rapidly once the shark is dead, which unfortunately is the condition most individuals are seen in.
Despite being discovered well over 100 years ago very few specimens have been recorded and little is known about their lives.
No pregnant female Goblin shark has ever been caught, but it is likely they are ovoviviparous like other members of the order Lamniformes.
They are a deep water species, typically found at depths of between 250 and 1000m near the sea bed, but young specimens have occasionally been seen in shallow water.
Stomach contents show a diet made up of squid, pelagic octopus, fish and crustaceans.
The largest specimen caught so far was a male measuring 3.8m/12ft but females may get even bigger.
They are thought to be resident in most of the world's oceans.
Why not check out some of our other Weird fish of the week features?
This week's weird fish caused a sensation back in January 2007, when video footage was released of a strange, snake like shark found swimming off the coast of Japan by a local fisherman.
The bizarre, alien looking fish featured was described on TV reports as a "living fossil" and its weirdness was enhanced by its oddly arched body shape, languid swimming style and gaping mouth filled with equally bizarre looking teeth.
It was captured and taken to a nearby marine park but unfortunately died shortly afterwards. Experts identified the fish as a Frilled shark, Chlamydoselachus anguineus.
The species is a relatively scare and seldom seen deep sea shark which usually only appears as by-catch from deep sea trawlers so has hardly ever been seen alive, but the images flashed across the world from this discovery are not exactly a true picture of this odd shark as the fish shown is clearly sick and near death. You can see the video footage below:
Despite these reservations they are still a good candidate for weirdness. Their long, almost eel-like bodies are not typical of what most people would consider shark-shaped and give them a look something like a stretched dog fish (Scyliorhinidae).
Their dorsal fin is small and situated far back near the tail, which is itself lacking the caudal notch associated with sharks.
They have exceptionally long jaws which are terminally positioned, rather than underslung like in the majority of shark species. These jaws are filled with lines of fine, tricuspid (three pointed), teeth. This combination of large mouth and fine teeth is believed to help them eat large prey, which once in the shark's mouth is unable to wriggle out again because of this hook-like dentition.
Stomach contents of captured specimens have shown that they appear to largely eat squid, fish and other smaller sharks. They get their common name from their distinctive frilly gill structure which is also a clue to their ancient lineage as they have six gill openings while 'modern' sharks have only five. Their scientific name is equally descriptive, 'chlamys' being Greek for cape/tunic/frilly and 'selachos' for shark, while 'anguineus' is from the Latin for snake-like.
Frilled sharks grow to around 2m maximum, with females being larger than males.
They are aplacental viviparous, the embryo's living inside eggs and hatching inside the mother at around 8cm then living off their yolk sac and also possibly gaining further nutrition in unknown ways from their mother until they are born at around 50cm long.
Litters are typically between two and 15. It has been speculated that the gestation period may last as long as three and a half years which would make it the longest of any vertebrate. This slow reproduction in combination with very limited knowledge of the species and an increase in deep water fishing has led them to be listed as 'Near Threatened' on the IUCN red list for endangered species.
In 2009 an ROV operating on the Blake Plateau off the south-eastern United States captured the first footage of the frilled shark in its natural environment which gives a better insight into how these fish look when alive and well.
A second, smaller species of frilled shark, Chlamydoselachus africana was described in 2009 and is found off the coast of southern Africa.
Why not check out some of our other Weird fish of the week features?
This week's scuttling sea bed oddity is the Sea moth or Little dragon fish, Eurypegasus draconis.
The more weird fish we look at, the more normal it seems for fish to walk around the seabed rather than swim, and the Sea moth is another well practiced perambulator at the expense of swimming ability – they've even dispensed with their swimbladder to make trundling around the sea bed easier. Check out the video below:
This walking behaviour is made possible by their specially adapted pelvic fins which are little more than the fin spine and the first ray joined to form an odd tentacle like structure used for this purpose.
Coming from the order Gasterosteiformes which is also home to the sticklebacks, they share similar armoured body characteristics to their prickly cousins, but taken to far greater extremes. Growing to around 12cm/4.5in, the Sea moth's depressed, flattened body is covered in hard bony plates, giving them a lumpy protective carapace which is so complete the fish sheds the whole structure in one piece when growing, rather like an aquatic insect.
This seemingly odd behaviour also helps rid them of algae, parasites and other hangers-on.
They have greatly enlarged pectoral fins which they can fan out from their sides, flashing bright edges in the process probably as a way of scaring off would be predators. When forced to swim these fins can be tucked back making these cumbersome creatures more streamlined. These wing like fins give rise to their common name.
They have a long, pointed rostrum, (nose) and underslung mouth with which they forage around the substrate in search of their prey, which consists largely of tiny crustaceans and worms found just under the surface.
Observations of these fish in the wild reports them often in pairs and they are thought to be monogamous. They show no parental care as they are broadcast spawners with breeding pairs leaving their sea floor sanctuary at dusk, swimming upwards into the water column where they release and fertilise eggs.
They are found at depths between 3-90m in the tropical Indo-Pacific but little is known of their lives.
Unfortunately their dried bodies,(and those of the four other Sea moth species) are increasingly being used in the Chinese medicine trade, often in place of the seahorses to which they are distantly related.
This has led to the IUCN red list of threatened species listing the fish as "data deficient" in a call for more research and scrutiny of Sea moths, and the trading of them. They are occasionally found for sale in the aquarium trade.
Why not check out some of our other Weird fish of the week features?
Few fish live up to their name as well as this week's aquatic oddity: the Mega-mouth shark, Megachasma pelagios.
Mega-mouths really don't look like any other shark. With their huge rounded head and gaping, down-turned mouth they always have a rather depressed look about them.
Their massive body, which can grow in excess of 5.5m long, tapers away after the head making them look rather like an gigantic tadpole until you notice their huge asymmetrical tail fin, the upper lobe of which is very long, similar to those of thresher sharks.
The whole shark has a soft and flabby appearance, not the sleek, streamlined profile most of us think of when picturing sharks.
They are harmless plankton feeders sifting their prey from the water with specially adapted gill rakers. Their feeding method is thought to differ from the other giant plankton eating sharks, (whale and basking) in that they are believed to suck prey into their mouth, close it and expel the water through their gills where the rakers filter our their prey, rather than swimming forward mouth agape, constantly filtering like their planktivorous cousins.
It was believed they had evolved from the same ancestor as basking sharks, but it is now thought they evolved their feeding adaptations independently.
Their diet seems to consist largely of euphausiid shrimp (krill), but copepods and jellyfish have also been found in their stomachs.
Very little is known of their natural behaviour, especially as the majority of specimens found have been dead, or near death, but a male specimen captured and re-released successfully with a radio tag attached in 1990 gave a brief insight into their behaviour. The tag showed the fish swam at a depth of between 120-160m during daylight hours but rose to between 12-25m at night. This behaviour is typical of many species that track to day/night migration of plankton. The tagged fish lived up to its sluggish looks, swimming at no more that 2.1kph during the recorded period.
The first Mega-mouth was discovered tangled in the sea anchor of a US naval ship off Hawaii in 1976 and was finally described scientifically in 1983. Since then only 50 specimens have been caught or sighted, making it one of the rarest and enigmatic shark species.
At adult size they have few predators, but one was seen being attacked by sperm whale. However all adult specimens discovered so far have shown scars or wounds left by the parasitic Cookie cutter shark, Isistius brasiliensis.
They are ovoviviparous, giving birth to live young which develop in eggs inside the mother before birth. As far as can be ascertained from the fish recorded so far they are distributed throughout the world's temperate and tropical oceans.
Why not check out some of our other Weird fish of the week features?
Fish that can walk and forage with their fins? This week's weird fish is sometimes to be found off our coast here in the UK: Dactylopterus volitans, more commonly known as the Flying gurnard. Check out the video!
The first thing to clear up is its name. Despite both common and scientific names suggesting otherwise, ('volitans' deriving from the Greek for flying) these fish cannot fly, or even glide. The purpose of their extravagantly enlarged pectoral fins seems largely to be as a defence mechanism. When disturbed they extend the fins, which are edged with bright blue, outwards and this display startles and confuses would be predators.
The weirdest thing about these odd fish though is their way of moving about and feeding. Rather than swimming they prefer to use adapted pelvic fins to 'walk' along the seabed in search of food.
The oddness continues as their prey of crabs, shrimp, other small crustaceans and fish are found with the use of two specially adapted parts of the pectoral fins, which have formed into what look almost like two hands.
The fish uses these to prod and poke about on the sea floor, pushing aside seaweed and pebbles, and washing away sand in an attempt to disturb and uncover any potential food which is quickly snapped up by the hungry fish. See all this in action in the video below:
These peculiar fin adaptations explain the first part of their scientific name which derives from the Greek words for 'finger' and 'fin'. They are capable of swimming in a more normal manner with their oversized pectorals folded neatly away, and do possess a swimbladder to help with this, unlike many 'walking' fish species.
Like the true gurnards or sea robins, the Flying gurnard can make a drumming sound by hitting their swimbladder – whether this noise-making capability is another method of startling predators, or for communicating with other Flying gurnards is unknown.
They are well protected fish, whose body is covered in large, scute-like scales while the bones of the head have formed a tough helmet.
These defensive measures make the Flying gurnard a surprisingly bold species, unconcerned by approaching divers, some of whom have reported the fish suddenly turning and ramming into them with their bony armour if their warning display is ignored.
Growing to around 50cm/20in, they are found throughout the Atlantic, as well as the English Channel, Mediterranean and Gulf of Mexico.
Weirdness isn't purely the reserve of marine fish, so this week I thought we'd look at a freshwater oddity, the Mississippi paddlefish or spoonbill, Polyodon spathula.
Coming from the same ancient order as sturgeons, and little changed from their Cretaceous ancestors of 145 million years ago, paddlefish look rather like a miniature basking shark with an oar stuck on their nose!
The similarity to the giant marine plankton eater is no coincidence as the paddlefish itself feeds largely on the zooplankton found in the sediment rich, slow moving, murky Mississippi river system of North America.
Growing to a maximum of around 2.2 m/7ft and weighing up to 100kg/220lb, these gentle river giants spend their time swimming with mouth agape, filtering their microscopic prey from the water with the aid of gill rakers (see the video below).
The bizarre paddle-shaped rostrum, which can be as much as 50% of the fishes' body length, is thought to serve a dual purpose, helping channel plankton towards the mouth while at the same time being covered in electroreceptors used to detect prey as well as navigate its murky habitat, day or night.
Tragically, like the vast majority of giant river fish species worldwide, the paddlefish is threatened within its native range with a number of factors at play in this situation. They are a popular food fish for both their meat and roe (sold as American Sevruga Caviar) and both legal and illegal harvest of the species are major population pressures, while introduced Asian carp (also filter feeders) are in many areas found in plague level populations and as a result outcompete the slower breeding paddlefish for available food.
Despite this the USFWS (US Fish & Wildlife Service) believe current populations (10,000+ adults) can sustain harvest at the present level, but the IUCN red list lists the species as "vulnerable".
There is one other species of paddlefish, Psephurus gladius known as the Chinese swordfish. This larger fish is native to the Yangtze river system but is listed as "critically endangered", with many believing it already extinct as the last confirmed sighting of a live specimen was in 2003.
It's time for another trip to the deep for this week's ocean oddity as we take a look at Nemichthys scolopaceus, more commonly known as the Slender snipe eel or Threadfish.
This strange looking fish certainly lives up to its name with a vastly elongated body, (up to 130cm/4ft 3in long) topped by a bulbous head with large eyes typical of many deep sea species.
Its spine is made up of around 750 vertebrae, more than any other animal species currently known on Earth.
The fish's jaws are greatly extended and curve away from each other at their tip meaning that they don't meet when the fish closes them. These slender jaws are filled with tiny hooked teeth with which the fish are believed to catch their prey by swimming mouth open, ensnaring any passing crustaceans on these toothy snags before swallowing them.
Another bizarre characteristic is that despite their huge body length, their anus is situated near their head, a short distance behind the pectoral fin. What benefit this adaptation, or their extreme length in general gives them is uncertain.
They have no distinct tail fin, instead their body ends in a long filament and they are thought to swim by means of a rippling motion of their extremely long dorsal and anal fins which both have over 300 rays.
Their scientific name is also very descriptive: 'Nemichthys' from the Greek words for thread and fish and 'scolopaceus' alluding to the fishes' long, beak-like jaws which resemble those of wading birds, such as the snipe, (from where it gets its common name) which are from the family Scolopacidae.
Little is known of their breeding, but degenerative changes in both sexes,(particularly the males whose jaws shorten with age) suggest they may be semelparous like many other eel species, dying after breeding.
They are distributed world wide in tropical and temperate seas usually at depths of 400m or below.
What's in your tank? Have you stuck to the 'natural look' â€“ or have you added a Roman ruin? Or a UFO? Maybe a fluorescent skull? Bob Mehen wonders why some fishkeepers put such strange things in their tanks.
Having kept fish of all varieties for a number of years now, it never ceases to amaze me what objects people will put in their tank in the name of decoration.
The range in most of my local shops is staggering, and for the amount of space dedicated to these items I assume they sell well – but who is it that buys them?
Most of us will start a new tank with a reasonable idea of the "look" we're trying to achieve. The bare bones usually involve some kind of substrate, a few rocks and pebbles, maybe some wood, and some plants – real or plastic.
Most people I know who keep fish are attempting to create something that offers an attractive back drop for the fish, while offering the fish themselves a comforting, more "natural" environment. There does seem to be another way though...
Now at this point I have to admit to subjecting my goldfish to living with a large ceramic skull in a feeble attempt to convince my non-fishkeeping school friends that I was in fact the proud owner of some piranha, and not a pair of shubunkins called Bubbles and Spot – in my defence I was only 10 years old, and my friends were very gullible, knowing next to nothing about fish.
This kind of behaviour probably explains the countless boggle-eyed "Nemos" and bubble powered LED crabs - not to mention the more traditional treasure chests, and "no fishing" signs. Children love all this kind of thing, and if it keeps them interested in the hobby long enough to actually become really interested in the fish themselves then it's probably a good thing.
What does confuse me is the increase of enormous underwater ornaments – well out of the reach price wise of the average 10 year old. I've seen huge sunken pirate ships, crumbling temples, large 1950s American pick-up trucks and even a wrecked Grumman Hellcat fighter plane, which unless you're planning a Bermuda Triangle biotope seems a very unlikely aquarium decoration.
Add to this various under water LED lights and bubble curtains and your tank could end up looking like the cast of Rome's end of shoot disco hosted by Liberace.
I wonder quite what some of the fish make of all this – one day you're minding your own business, swimming up a tributary of the Amazon, then you're whisked halfway round the world into a tank full of illuminated goat skulls and UFOs... How would you feel?
Now all these things are a matter of taste I suppose – "whatever floats your boat", (or at least whatever lights up your boat in rainbow colours while emitting bubbles from a giant plastic octopus) – but I have to ask who is it that buys these things, and are they really part of the "best" environment for our fish?
What's the strangest object you've seen or put in a tank? We'd love to know! Why not send a picture and tell us a bit about it to email@example.com
Are fishkeeping books a thing of the past, asks forum moderator Bob Mehen.
I was flicking through my collection of books on fishkeeping, when a thought suddenly struck me – are books really the best way of communicating knowledge and advice in the hobby today?
When I started keeping fish in a serious way in the mid 1980s, there were three main ways of learning new information on techniques and fish species. You either read a book, joined a club, or went to your local shop and asked the large man with a beard behind the counter, (all shop owners in the 1980s seemed to fit this description).
Now this being the 21st century, things have changed, (although possibly not the large man with a beard).
The most obvious one of these being the advent of the internet and websites and forums like the ones run and hosted by Practical Fishkeeping. This is undoubtedly the most dynamic area for expanding your knowledge – there are a host of websites out there – and as long as you read the more reputable ones then the advice tends to be up-to-date, and well researched.
The problem with books is the fast changing nature of the hobby today. I haven't been involved with writing or publishing books, but I imagine that it isn't a quick process - you'll need to pitch the idea, write out the draft, sort out the pictures and layout etc.
All this must take some time, and it wouldn't surprise me in the slightest if by the time the book has finally been published that some facts will be out of date.
Take taxonomy for instance - with new DNA techniques, re-classification of already described species seems an almost daily occurrence, so just as you get used to your Corydoras, you discover that in fact you're keeping Scleromystax (pictured above).
This is where magazines and the internet become ever more important. They are able to keep pace with this change, where as a book released just a year ago can appear terribly dated.
The techniques and technology of the hobby seem to be changing faster than ever as well, particularly in the areas of marine and planted aquaria where new ideas seem to be as fertile as the substrate in one of George Farmer's tanks.
I have several books published in the last five years which show things such as undergravel filters, canister filters which appear to have been cobbled together from old buckets and gaffer tape at home and go to great lengths to describe cycling your tank with hardy fish.
Although the basics of keeping many fish are the same as they ever were, and the main point of all the technology we employ is to keep the water as stable and clean as possible, the means by which we achieve this have changed dramatically.
Reefs have gone form externals, to wet and dry filters, to live rock 'Berlin' method, sumps, algal refugiums, deep sand beds and Miracle Mud, ULNS – who knows where it'll go next? One thing that seems certain is by the time the book is published to describe this 'new' method it'll already be the 'old' way!
With clubs disappearing at an alarming rate, and reliable information on the internet and in monthly magazines so easily and cheaply available, are books on the hobby increasingly a thing of the past?
This week's weird fish is surely one of the more odd species regularly offered for sale in the marine hobby, Monocentris japonica, commonly known as the Pinecone fish.
These spiky customers certainly live up to their common name with a body covered in large bony scutes, (plate-like scales), most of which are topped with ridges or spines.
Each of these armour plates is boldly edged in black which contrasts beautifully with their largely yellow body.
If this fearsome protective covering fails to ward off the unwanted attentions of any hungry passing predators then the fish is also equipped with enlarged, lockable dorsal and pelvic fin spines to stick in the throat of anything foolhardy enough to try swallowing them.
These fish are largely nocturnal which helps explain another weird thing about them – two bioluminescent light organs,(photophores) on either side of their chin. This light is produced with the aid of a symbiotic bacteria within the photophore and it is believed to help attract zooplankton which make up much of their diet.
They are a shoaling species and it has also been suggested that the light may act as a form of communication between the fish.
Found largely in the sublittoral zone, (the area of sea where sunlight can reach the ocean floor) they spend the day in caves or under ledges and rocky overhangs of reefs, waiting for darkness to fall when they venture out in search of food.
Growing to around 17cm/6.5in, they are found in the Indo-West Pacific from South Africa and the Red Sea eastwards as far as Australia and New Zealand.
As an aquarium subject they are generally considered difficult to maintain long term, with a large percentage believed to perish before they even reach the hobbyist due to poor handling and lack of appropriate food among other issues.
Another similar species is also sometimes imported, the closely related but larger Pineapple fish, Cleidopus gloriamaris which, besides its greater size, can be distinguished from M.japonica by having a blunt, more rounded snout.
On the January 28-29 2011, Dan Crawford and George Farmer represented the UK in an international live aquascaping contest in Hanover, Germany. George Farmer reports...
This competition is held every year, as part of a pet trade show. It attracts aquascapers from all over the world. This year included the Russian winner from the IAPLC 2010, regarded as the world's most prestigious aquascaping contest. Other entrants included Oliver Knott.
Dan and I took part, as the only UK contestants. We were invited over as part of the 'Rainforest' team who are a German TV production company. I was interviewed several times times during the contest, for TV. Their main site is www.aquanet.tv
The tank we set up was part of the 'XL' category - 100 x 50 x 50cm. There were 32 entrants. There was also a nano category with Dennerle 20L nano tanks - 37 entries.
The 100cm tanks were fitted with 2 x 39w HO T5, with external filter and heater. Substrate was supplied if required but all plants and decor you needed to source yourself.
The top ranking aquascape is shown above. Below are the second and third ranked aquascapes.
copyright © Jørgen Fischer Ravn
copyright © Jørgen Fischer Ravn
The standard was incredible, as you can see. Most aquascapers had spent months in advance growing-in their plants and aquascapes prior to the event. This is why they look mature. We were at a disadvantage because we used brand new emerged potted plants. Next year we will be better prepared.
The aquascape next to ours was grown on a 100 x 50cm piece of filter sponge. This way it could be transported from the entrant's home to the event and set up within a hour.
In contrast, Dan and I spent around 12 hours planting almost 1000 individual plant portions in an attempt to achieve a mature-looking aquascape.
There were many German entrants who also had the advantage of living relatively near the event. Dan and I drove over 1,200 miles in total.
I think our entry was the most natural-looking layout. The winning 'scapes all had mature plants, wood and open sand areas, so that's an interesting observation. There was some new plants to the hobby, including a bonsai version of Hygrophila pinnatifida.
The Danish contestants were the most friendly and we spent a lot of time together, eating, drinking and talking about aquascaping.
copyright © George Farmer
We didn't come in the Top 10 which was disappointing, but given the excellent overall standard and quantity of 'scapes with mature plants, it's no surprise. Our entry is shown above.
Next year will be interesting, as we know what to expect...
There's a video, but the final production will take some time.
More details can be found here.
Look out for full feature on the event in a forthcoming issue of Practical Fishkeeping magazine.
This week's candidate for Weird fish of the week is another occasional aquarium subject, the Razor or Shrimp fish, (Aeoliscus strigatus).
There's little about these strange fish that isn't weird when compared to what most of us would think of as 'normal' fish anatomy.
The obvious oddity of the Razor fish is its swimming position - they swim in a vertical position with their heads pointing downward and their tails up.
This odd method of locomotion is made possible by some extreme body adaptation. Their dorsal fin is divided into two parts, the first of which is positioned on the end of the body where the caudal fin, (tail) would normally be, while the second dorsal and true caudal are positioned ventrally beside the anal fin.
This peculiar arrangement means the fish moves around using a sculling motion of its pectoral fins in combination with waving movements of the adapted dorsal, caudal and anal fins, sometimes described as 'Balistiform swimming' after triggerfish which employ this method themselves.
Razorfish are generally a shoaling species and groups of them achieve an impressive degree of synchronisation in their movement. Their cryptic swimming method make sense when they are seen in their natural environment, hidden among the spines of large Diadema sea urchins, sheltering among branching staghorn corals or gorgonians and hiding in sea grass beds. Here their vertical stance, along with a dark bar running from nose to tail means they can hide from both predators and potential prey such as copepods and zooplankton which they snap up in their tiny, toothless mouths.
They come from the order Syngnathiformes which includes the seahorses, pipefish and ghost pipefish with which they share another weird characteristic. Their bodies are covered with a series of transparent bony plates rather than scales which make them rigid and they taper to a sharp edge on their ventral surface. This gives rise to their common name as their hardened, laterally compressed bodies look rather like a cut-throat razor.
Growing to around 15cm/6in long they are found in the Indo West Pacific from Tanzania and the Seychelles to Southern Japan and New South Wales, Australia.
Why not check out some of our other Weird fish of the week features?
This week we take a look at the Hairy or Striated frogfish, Antennarius striatus, a fish that will be familiar to some as it appears from time to time in the hobby. Check out the video too!
These fascinating predators certainly live up to their common name as they're covered in thousands of fleshy, hair-like skin extensions helping to blend them in among soft corals, sponges and sea weed or simply break up the general shape of the fish when hunting on more exposed sandy areas.
It has also been suggested that these 'hairs' mimic the spines of sea urchins.
They are also able to change colour to match their surroundings further disguising themselves.
These hirsute hunters seek out their prey in two main ways, the first of which is typical of many members of the order Lophiiformes, (commonly known as anglerfish). The frogfishís first dorsal fin spine, (known as an illicium) has evolved to move independently and is topped by a fleshy lure or 'esca' which the fish twitches and sways to simulate the movements of a marine worm.
Any unwary prey tempted within reach is engulfed with lightning speed into its capacious mouth. Their stomach is also expandable and they have been known to swallow fish twice their own size.
The other way of hunting employed by the frogfish is to stalk potential prey across the seabed using highly developed pectoral and pelvic fins which resemble arms. These are used to slowly 'walk' up to their target before attempting to swallow them whole.
They have also been observed searching for the burrows of small fish before positioning themselves nearby and 'fishing' for their meal with their lure.
They are poor, reluctant swimmers and usually only do so to flee predators and have also been known to inflate themselves with water like puffer fish as a defence mechanism. This water can be released through their tube-like gill openings to give them a form of jet propulsion to further aid escape.
Females grow to around 25cm/10in, while males are usually considerably smaller at closer to 12cm/5in.
Courtship can be a risky affair as hungry females aren't averse to eating any careless potential suitor that approaches without due caution.
On first inspection the Cookie cutter (Isistius brasiliensis) looks an unlikely terror of the deep, but looks can be deceptive!
Cruising through the moonlit sea, a tuna spots the tell tale shape of a small fish silhouetted against the oceans surface and moves in for an easy meal. What happens next isnít exactly what it expected. At the last moment the predator's meal disappears and suddenly it's more a case of 'the biter bit' as something small and toothy clamps onto its side, bites hard, spins and disappears into the night leaving it with an empty stomach and a nasty circular wound on its side.
This scenario plays out time after time, with whales, dolphins, sharks and seals as well as fish the unwitting dupes of a weird but effective feeding strategy that makes Isistius brasiliensis a success across most of the world's oceans.
Growing to around 50cm/19in long, the Cookie cutter shark's cigar-shaped body has greatly reduced finnage other than its tail - this is no ocean cruiser - it is adapted for a short explosive burst to latch onto its victim.
The disappearing trick it uses to attract its prey is thanks to what is thought to be a unique use of bioluminescence in a predatory fish.
The Cookie cutter's belly is covered in photophores apart from on a small dark 'collar' under the fishes' gills. It is speculated that using 'counter-illumination', (matching its light output to the light penetrating from the sea's surface) the fish becomes invisible apart from the dark collar which appears to be a small fish to any would-be predator lurking below.
They are believed to swim at different levels in the water column to compensate for the ever-changing light levels above them. The shark's fearsome dentition, (the largest in comparison to its size of any shark) rapidly removes a bite sized chunk of its victim with the smaller upper jaw teeth gaining purchase while the larger lower teeth slice through flesh.
The mouth itself is modified to form a suction cup to gain further grip. Occasionally Cookie cutters have been known to bite off more than they can chew. Attacks by them on the neoprene covered sonar domes and electric cabling of US submarines caused several subs to need emergency repairs and the installation of fibre glass covers in the 1970s and 80s.
They are considered facultative ectoparasites as they are also known to eat smaller prey such as squid completely. Related to dogfish, they are ovoviviparous, giving birth to litters of 6 to 12 pups which are around 15cm/6in long.
This week's featured species is Neoclinus blanchardi, commonly known as the Sarcastic fringehead. And if you think it's just the name that's weird, check out the amazing video below!
The 'fringehead' part of its name is fairly self explanatory, as these fish have soft tissue tentacles on the front of their heads, but as for the sarcastic part, who knows? It seems unlikely that the fish uses harsh or bitter derision in its daily life off the East Pacific coast of California and Mexico, so perhaps the 'sarcastic' name comes from its aggressive territorial behaviour, sarcastic being another word for taunting?
These feisty fish spend much of their time living inside old mollusc shells, clam burrows or any other structure that offers them a defensible outpost in their generally otherwise barren sea bed environment.
This paucity of suitable homes has led to them becoming extremely territorial when they do find one, and to this end the fish has evolved a truly weird way of sorting out disputes.
At first glance these small, (around 30cm/12") fish are rather non-descript, with little more than a couple of bright yellow marks on the side of their jaw to break the otherwise largely cryptic pattern of brown, black and white markings, but when faced with another fringehead interloper on its patch, it reveals a truly weird adaptation.
Their upper jaw has loose joints where it would normally hinge with the lower, and a pivot between the two loose sections at the snout allows the fish to rapidly extend their large mouth outwards to form a triangular frill, edged with bright yellow. See this all in action below.
This bizarre display is used to measure up with other fringeheads as the two quarrelling fish first compared gapes, and then if unperturbed by the comparative size of each others' chops, a battle will ensue with each fish seeking to push the other back, while engulfing them with their mighty mouths.
Females lay eggs inside the male's shell or burrow home which he guards with typical pugnaciousness until they hatch.
Why not check out the other Weird fish of the week features?