Treasures of Pirate Island

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Chris Lukhaup and Stefan Hummel find shrimp, snail and plant gems galore in three habitats of an Asian outpost that's still simmering with internal unrest. Translation by Ulli Bauer.

The volcanic Indonesian island of Sulawesi was once inhabited by bloodthirsty pirates spreading fear among passing seafarers. Today the languages of ethnic groups there differ greatly, even though they have been living, somewhat uneasily, on the same land mass for centuries.

They have been isolated by the very geography of this octopus-shaped island once known as Celebes. It’s midway between South-East Asia and Australia and physically partitioned by steep and rugged sierras.

Between 1998 and 2006 conflicts between Christians and Muslims on Sulawesi resulted in more than 1,000 deaths. Currently, emotions have cooled and news has filtered out about some fabulous freshwater inverts there.

Numerous attractive snails have recently been discovered in the island’s Malili lake system, including some beautifully coloured and patterned shrimp. Many waterplants found there have still to take root in the hobby, though.

Naturalists Wallace and Weber have contributed greatly to the exploration of the island. They found Sulawesi to be a link between Asian and Australian flora and fauna, but most plants and animals there are endemic.

My colleagues on our expedition there were Stefan Hummel, the Logemann brothers from Hamburg and Thomas von Rintelen of the Natural History Muesum in Berlin. After a day-long journey from the provincial capital of Makassar to the northern port of Poso we immediately went invert hunting.

Small white Fiddler crabs of the Uca genus, as well as some hermit crabs, indicated a brackish habitat for the area.

We also found a group of Faunus ater snails in shallow water. These grow to a shell length of 8-9cm/3.1-3.5” and live mainly in the mouths of small to large rivers, grazing on the muddy ground. They have also been reported in heavy currents and pure freshwater, but also in brackish lentic waters — even marine conditions.

Turning with tides

When the tide was low, they moved towards the sea some 50 metres away with the freshwater from the river and returned with the flood tide.

Not much is known of their reproductive biology, but their distribution suggests larvae hatch from their eggs, needing marine conditions to grow, and they re-migrate to freshwaters when developed as snails.

We then ventured into the highlands, finally reaching the sparkling blue waters of Lake Poso and on the sandy beach immediately found shrimp and snail species where the water was a cosy 28°C/82°F.

At first glance the bottom appeared empty, but a closer look revealed Caridina ensifera (above) and Caridina longidigita shrimp, several crabs, gobies and more than one Tylomelania species of snail on the rocks and in mud.

We chartered a boat to a small, remote bay on Lake Poso’s western shore. Alone on this dream-like beach we found beautiful Caridina ensifera on rocky to pebbly ground in shallow water. When the water reached a depth of 1m/3.3’ we found groups of Caridina caerulea (pcitured above) sitting on every submerged tree trunk and branch.

This shrimp species has been introduced in the hobby as Blue Morphe. Usually these have a long blue rostrum, but their bodies are more or less transparent and only their tail fan carries two striking blue dots. However, some specimens have all-blue bodies.

In Lake Poso, they are not as common as C. ensifera, which display a similar pattern but the coloured areas are red instead.

Blue Morphe shrimp are mostly found on rocky ground, on wood or on pebbles, and sometimes on softer substrates like aquatic plants. This is the only blue species in the lake, as most of the others are reddish or brown.

We also saw yellow Tylomelania sp. snails on rocks as well as mud, but they seemed to prefer a hard substrate as their offspring were 1-2m/3.3-6.6’ down on boulders. Their dark brown to black shells show a pronounced spiralling and axial sculpturation, their bodies being bright yellow to orange.

We did not get to find any large specimens, though, as we had to return to the surface. To find adult snails you really must have proper diving equipment!

We saw C. longidigita in the crevices of rocks on the shore, constantly filtering water for food with their tiny fans.

Lime layers

A few kilometres and 3,500 potholes later we came to a spectacular waterfall with thick lime deposits — the home of Tylomelania sp. ‘Thunderbolt’. This river carries so much calcium oxide that its deposits cover everything. Even the mosses and tree roots in the splash zones are coated by a whiteish layer of lime.

Next morning a rented boat brought us to a rocky shore a few kilometres off the island of Ternate and home to quite a few hitherto undescribed snail species Thomas had collected in 2007.

It was windy, waves were high and filming almost impossible. We planned to return later with a small dragnet, as many of these new snail species are only 9-10m/30-33’ down.

We adjourned to a bay with shallow, calm water, covered by a carpet of floating Nymphaea indica leaves and thousands of the small, attractive flowers shimmered in the noon sun. The Indian Water Lily is, however, hardly useable in aquarium tanks as it exclusively develops floating leaves.

We circled 100m/330’ offshore where depth was around 10-15m/30-33’ and drag netted some of those new Tylomelania. One was a red and white beauty, with green eggs. 

We lowered the net several times and found even more new shrimp and snails.

Next day we were scheduled to go to Lake Matano in south Sulawesi, taking a bumpy ride to a brook which seemed perfect for shrimp — but proved otherwise.

However, Stefan discovered a miniature waterfall in dense jungle en route, with beautiful mosses growing on the rocks and tree roots around it. He found a coral moss of the Riccardia genus there from the Arneuraceae family and highly prized.

Shortly before we reached Lake Matano we stopped by a river and the habitat of two new crab species. We also collected the Sulawesi Bee here — these small shrimp preferring areas with weaker currents.

Their rostrum is extremely short, looking as if it had broken off just behind the eyestalks. They live on rocky substrates and should kept as such in aquarium tanks with lots of rock structure. They mainly eat aufwuchs and will breed in captivity, although not an ‘easy’ species. The females carry more eggs than other Sulawesi shrimp.

One species, very small and similar to the Micro crab (Limnopilos nayanetri) seems to belong to a new genus hitherto unknown from Sulawesi and it is now being closely inspected.

After a five-hour drive we arrived at Nuha, a hamlet in the north of Lake Matano, where a ferry took us to the mining town of Soroako.

The lake is more than 600m/1,970’deep and home to some of the most beautiful freshwater shrimp and we found the Cardinal (Caridina dennerli), named after the Dennerle plant specialist company, at a rocky reef.

This species (pictured above) has so far only been found here, hidden among rocks of the coastal zones down to around 10m/33’. Their usual colour is red, with white dots, but some have blue dots or larger blue spots.

If they get stressed they can turn blue, but only for a few minutes. Often they are dark red in the morning, fading to light red in the evening — seemingly according to their moods.

Moving feet

In the aquarium, Cardinal shrimp are often shy and remain hidden in rock crevices all day, as in nature. These are best kept in a dedicated tank where their white claw feet will keep moving, grazing aufwuchs from hard surfaces.

Our next location was a small island and under leaf litter and rocks we found Caridina holthuisi, C. lanceolata, C. loehae and many Tylomelania snails. There were even Matano crabs at 2-3m/.6.6-9.9m down.

C. holthuisi (above) is found in Lakes Matano, Mahalona and Towuti, and a population is known from the Petea river, preferring to live in leaf litter or detritus, sometimes on waterplants. They are usually dark brown to black to confuse predators, but some are white or cream-coloured to blend with where they live.

C. loehae are distributed all over Lake Matano and live down to 5m/16.5, as well as in places like Lake Towuti and the Petea river.

As rock dwellers they share their habitat with C. dennerli and C. parvula. They are red or reddish brown and have white dots as well as a characteristic cream-coloured stripe across their back.

After transportation they may go purple or blue, but, after adapting, will return to their original reddish.

We rounded the island underwater amid impressive populations of Ottelia mesentherium. From the family of Frogbit (Hydrocharitaceae), this plant is endemic to Sulawesi and only found in the Malili lakes.

Ottelia grew at a depth of around 80cm-3m (32”-10’) and its crimped leaves look similar to Crinum calamistratum, originating from Africa, and and were particularly deep rooted.

The shallow water of another bay was densely overgrown with stonewort, an algae that looks much like hornwort.

Closer inspection revealed a fantastic local population of Ottelia alismoides, a perennial that reminds a bit of a waterplantain of the Alisma genus — hence the species name alismoides.

Bizarre bushes

On the shore there were bizarre Pandanus bushes, among which was a large patch of Eriocaulon, and a close examination found at least four growth forms varying between 1-2cm to 6-7cm (0.4-0.8” to 2.4-2.8”).

Typically, these plants will display firm, almost throne-like leaves.

The Eriocaulon fields were interspersed with several stoneworts of the Chara genus and it’s still unclear if they can be grown in aquaria.

A special botanical surprise then revealed itself — a miniature plant of the Lymnocharus genus. Its shoots are tiny with thicker ends and plants are only a few millimetres high. Despite this, they have an enormous root system.

This sandy area on the shore was also home to carnivorous plants and in thick leaf litter in shallows we found some Caridina holthuisi.

Our last spot revealed underwater ‘scapes that reminded us of Amano creations! Here we found a great variety of Tylomelania species, Cardina shrimp and even fish of the Telmatherina genus, of which the males, shimmering in yellow or blue coloration, were performing mating dances.

The dominant plant was again Eriocaulon, along with populations of Lymnocharis. The thin stems of their floating leaves looked like fishing lines in the backlight. What incredibly mystic scenery!

Departing for Lake Towuti, we chartered another boat and at 1-2m/3.3-6.6’ saw the tiny white claw feet of freshwater Harlequin shrimp (Caridina woltereckae). They sat in rock crevices, hidden and protected. Around the rocks, several large tilapias circled. These food fish were introduced some years ago and predate heavily on shrimp.

This shrimp’s red and white striping is quite striking, even though some specimens may be less intensively coloured than others. Some are even transparent with light red stripes.

Such typical striped patterning is misleading, looking similar to C. spongicola. However, the latter are only found in one spot in the lakes and live exclusively in and on freshwater sponges. The Harlequin lives on hard substrates.

Rocky retreats

As the sponge is often found with other dwarf shrimps it may also be kept with them in aquaria. In the tank, specimens need lots of rock structures to retreat into crevices.

They do not breed easily in captivity and few specialists have succeeded. In any case, they have low numbers of offspring.

Caridina spinata are similar. Rock dwelling, they also originate from Lake Towuti and are usually found on large trunks or pieces of wood down to 3-5m/10-16.5’. Adults live in the lower areas, scavenging for food with other rock dwellers.

They have variable patterns —from a deep dark red with orange or yellow cross-stripes and dots of almost solid orange.

This species belongs to the larger groups of the lake and can be easily told part from others in the same habitat by striking colouration. Being highly susceptible to stress, they should best be kept in a dedicated tank.

However, they can be co-housed with Tylomelania snails that also live in Lake Towuti.

The scenery was beautiful on the shores of the Tominanga river, although we gulped when approaching the first rapids. It didn't help when Thomas told us his boat had keeled over in this very spot in 2004. Chins up, we went through and 20 minutes later reached Lake Mahalona.

Floating crocodile

We stopped at a shallow area and immediately went into the water. Beautiful Ottelia and Sulawesi grasses grew there, most endemic to Lake Mahalona, as were most of the Tylomelania species we found. On the shore we came across crocodile traces, so returned to the boats to explore another spot.

After a few minutes aboard we even saw a crocodile relaxed and floating on the lake!

A small rock mass offshore suggested that its sharp edges would be quite uncomfortable for the soft bellies of the crocodiles  we knew inhabited these waters so, going in, we witnessed unsurpassed underwater scenery.

The plant community was again characterised by cacti-like Eriocaulon species and those small Lymnocharus, with their line-like stems and tiny white flowerlets, were also in large numbers.

On another spot on the shore we saw several Eriocaulon growing above the waterline — a hint that they might also grow emerged. During the low water season some probably grow on land for several months.

When we ventured inland a few metres we found a gorgeous population of Limnophylla aromatica, its stems growing outside the water, too. Underwater they were olive green and above a blackish red with purple flowers. L. indica is widely distributed over South-East Asia, but not often found in aquatics.

On our return we had to cross Lake Towuti again and met a shrimp collector filling already crowded containers. Our suggestions to put in less shrimp and more water fell on deaf ears!

However, he invited us to look at his storage facilities in Timampu. This hamlet on the shore of Lake Towuti is home to several shrimp collectors. Here, these shrimp start their journeys to Europe or Asia — and into our hobby.

Where we collected

Lake Poso: Temperature 27.7°C/81.9°F; pH 8.1; GH 5; KH 4; conductivity 109 µS/m; oxygen 7.05 mg/l.

Lake Matano: Temperature 28.7°C/83.7°F; pH 8.5; GH 7; KH 5; conductivity 175 µS/m; oxygen 6.93 mg/l.

Lake Towuti: Temperature 29.2°C/84.6°F; pH 8.4; GH 6; KH 4; conductivity 146 µS/m; oxygen 7.15 mg/l.

The river in which we found the Sulawesi Bee shrimp (Mambo bee) had a water temperature of 23.2°C/73.7°F; pH of 8.3; GH 12; KH 6; conductivity 289 µS/m and oxygen 7.42 mg/l.

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