Best of Sulawesi 2023: crabs

Crabs from Sulawesi are very popular, but they still represent only a kind of curiosity, an addition to the aquarium. No one systematically deals with their breeding. We still make mistakes in inappropriate food, space and its equipment, we don't really know how crabs live in nature. Many of the Sulawesi species are still unknown to aquarists, and this also applies to the crabs that live in Lake Poso and the Malili system. I consider it almost certain that there are even still scientifically undescribed species.

Sulawesi Keepers will continue to focus intensively on crabs. I consider a good knowledge of natural conditions to be the very basis of our efforts to manage keeping (and breeding!). Observing the crabs in the lakes is very informative. For this article, I have selected several pictures of crabs that show the lesser-known species and aspects of crab life:

Syntripsa molluscivora is the most recently (2008) described crab species from the Sulawesi lakes. It is endemic to Lake Poso and is the only local crab that specializes in eating snails. This is evidenced both by its name and the specially adapted claw with "cracking teeth". In the Malili lakes we find two equally specialized species that are well known to aquarists: Syntripsa matannensis and Syntripsa flavichela.
Parathelphusa sarasinorum is a generalist, although this huge individual also has distinct teeth for cracking shells. In Lake Poso, this crab can be found on the open bottom, and it also climbs the rocks pretty well. The one in the photo is running away because I surprised him too close.
Migmathelphusa olivacea, another dexterous climbing crab from Lake Poso. I originally photographed shrimps (Caridina caerulea) on the wood all around, many of them are also sitting completely motionless with their head down on the rock around the crab. Crabs cling perfectly with their feet to the rough surface of the stone. I found many crabs (of different species) upside down in rock crevices.
Parathelphusa possoensis, another crab from Lake Poso. For the correct determination, the crab needs to be seen from different angles.
These tiny baby crabs, caught by shrimp collectors in Lake Towuti, belong to the species Parathelphusa ferruginea and Syntripsa flavichela.
Parathelphusa ferruginea is photographed here in Lake Towuti. The picture shows a tiny baby in the company of a fully grown individual. The situation is not arranged, this is how I found them at a pile of stones in the middle of an otherwise flat soft bottom with no shelters.
And once more Parathelphusa ferruginea. We know three forms with different leg colors, this one is particularly attractive.
Nautilothephusa zimmeri is a less abundant species from Lakes Towuti, Mahalona and Matano.
A rock surrounded by the remains of various shells? You can bet you'll find a snail-eating crab under it. Here it is a well-camouflaged Syntripsa flavichela (front of rock on the right).
Parathelphusa pantherina is undoubtedly the most popular species of crab from Sulawesi. This is not a very good photo, it was taken already in low light in the late afternoon. However, it captures a huge male that had an almost black and nearly circular carapace. Adult "panthers" move relatively quickly over longer distances, do not stay close to shelters and frequently meet other individuals.
We say goodbye to Lake Matano and the second local endemic: Syntripsa matannensis. This is a very young individual that I found while looking for shrimp under rocks. Notice the algae, which unfortunately covers an ever-increasing area of the lake bed…
See also the other selections of the best of the 2023 Sulawesi trip:

Markéta Rejlková