Crinoid Squat Lobster (Allogalathea elegans) is also known as the Feather Star Squat lobster or the Elegant Squat Lobster

Crinoid Squat Lobster-Facts and Photographs

Crinoid Squat Lobster (Allogalathea elegans) is also known as the Feather Star Squat lobster or the Elegant Squat Lobster

The Crinoid Squat Lobster (Allogalathea elegans) is also known as the Feather Star Squat lobster or the Elegant Squat Lobster. Although they are called squat lobsters they are more closely related to Hermit Crabs than Lobsters. They are also a lot smaller and are more cryptic than most lobsters. They are most often found in Feather Stars (Crinoids) hence their name.

Crinoid Squat Lobster (Allogalathea elegans) is also known as the Feather Star Squat lobster or the Elegant Squat Lobster

APPEARANCE

Crinoid Squat Lobster are roughly of a tear drop shape with an extended rostrum, the first set of chelipeds are longer than the body and have pincers on them.  The last set of legs are not developed and can be seen as orange colored in the images, The eyes are set up on the front of the body on either side.  The legs are patterned to resemble the arms of the host crinoid and the although the overall coloration varies they tend to have longitudinal stripes on them of a similar color to the host, often matching the color of the hosts legs. In the image below there are two specimens, but one has to look quite hard to see the second specimen to the left of the legs.  Females tend to be larger than the males and grow up to about 2 cm in length.

Crinoid Squat Lobster (Allogalathea elegans) is also known as the Feather Star Squat lobster or the Elegant Squat Lobster

CRINOID SQUAT LOBSTER IN THE WILD

Crinoid Squat Lobster are only usually only seen during daylight which in a way is surprising because one seldom sees Feather Star crabs or shrimp out during the day. They are sometimes found in pairs but may be solitary. The smaller specimens can be quite difficult to spot however and may be lower down on the crinoid near the base of the arms or on the legs.  They go through four zoel stages after hatching before turning into a miniature version of the adult. Their relationship with the crinoid host is said to be commensal  The squat lobster benefits from protection against fishes who will prey on them and given that both the host and the squat lobster are planktotrophic feeders, the crinoids move around and  choose the best possible spot to filter feed. Possibly the squat lobsters keep the crinoid’s free of other more harmful parasites. As with all crustaceans they molt at regular intervals and grow in size and just after the molt their exo-skeletons are very soft making them vulnerable to predators.

Crinoid Squat Lobster (Allogalathea elegans) is also known as the Feather Star Squat lobster or the Elegant Squat Lobster

HABITAT

The Crinoid Squat Lobster are found on crinoids across the Indo Pacific area from the African coast across to southern Japan and south to Australia. They are usually found shallower than 22 meters and we have not seen any deeper than this. There is evidence from a DNA studythat shows that there are at least four clades across the Indo Pacific area and that to quote the study “Allogalathea elegans is in fact a species complex comprising four different species, which, although genetically very distinct, are morphologically very similar”.  Undoubtedly in the future the specimens from each area will be re named. The specimens in the post were all photographed in Tanzania.

Crinoid Squat Lobster (Allogalathea elegans) is also known as the Feather Star Squat lobster or the Elegant Squat Lobster

DIET

Crinoid Squat Lobster eat planktonic matter off of their hosts and possibly catch some using their claws as it moves past.

Crinoid Squat Lobster (Allogalathea elegans) is also known as the Feather Star Squat lobster or the Elegant Squat Lobster

REPRODUCTION

The Crinoid Squat Lobster  tends to live in pairs on a crinoid and have been recorded breeding by various researchers.  Males chemically detect when a female is fertile and approach them.  Once the eggs are fertilized they are kept on the underside of the female. When the eggs hatch the larvae go through several zoel stages.  Females produce three to four broods per year and breeding among females in an area is synchronized.

Crinoid Squat Lobster (Allogalathea elegans) is also known as the Feather Star Squat lobster or the Elegant Squat Lobster

AQUARIUMS

Crinoid Squat Lobsters are reef safe and adapt well to aquariums, by all accounts readily switching over to frozen food. Thy do not require a crinoid/ feather star as a host. These are very difficult to keep in aquariums.

Crinoid Squat Lobster (Allogalathea elegans) is also known as the Feather Star Squat lobster or the Elegant Squat Lobster

CRINOID SQUAT LOBSTER CLASSIFICATION

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Family: Galatheidae
Genus: Allogalathea
Species: A. elegans

 

LITERATURE CITED

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