Crustaceans have a hard outer horny shell with jointed legs, obvious eyes often on stalks and segmented bodies species includes Crabs, Crawfish, Lobsters, Prawns and Shrimps.
There are over 4500 species of crabs, though there are relatively few to be found easily in this part of Turkey. These walking decapods belonging to the division (Brachyura) and are usually strong and powerfully built with a heavy exoskeleton. The carapace is flattened and rounded with the abdomen much reduced and folded forwards under the carapace. Antennae are usually short and the first pair of walking legs usually bear powerful claws. The other legs normally end in a claw like joint. Crabs have the most efficient method of walking of all the bottom walking crustaceans and is distinctive by their sideways gait, consequently they can achieve some speed.
These familiar seashore animals are easily recognizable because of their association with empty gastropod shells which protect their delicate soft skinned abdomens. Their body is adapted to occupy the typically right handed spiral of these shells though they can be found in a variety of other shells. They have the ability to assess the size and suitability of a shell by touch. Hermit crabs are carnivorous scavengers of the sea bottom. A little patience is required to see them extend their legs from their shell and scurry along the bottom. At the first sign of danger they withdraw quickly into their shell covering the entrance with one or both of their comparatively large claws. Many species can be seen in Turkish waters and the one most likely to be observed is the COMMON HERMIT CRAB (Eupagurus bernhardus), inhabited shells should of course not be taken.
LOBSTERS and CRAWFISH
Belonging to the suborder (Reptantia), lobsters and crawfish are walking decapods which live on the shore or seabed. They are strong and powerfully built and have heavy exoskeletons. The first pair of walking legs sometimes carry large claws, the other four pairs of legs are strong with pincers or claws. The last pair of abdominal appendages are modified to form a tail fan.
Some species are fairly common in Turkish waters but are rare within the permitted diving areas because they are taken for the table as soon as they are found.
SPINY LOBSTER (Palinurus vulgaris)
This is the most successful species of lobster found around Turkish shores possibly avoiding capture because it hides in rock crevices during the day venturing out usually only at night to feed. It has no claws but is recognizable by its two long antennae, it has extremely sharp spines and has to be handled with extreme care. Brown or red in color it can grow to 50cms in length, but this is unlikely in regularly dived areas.
Another species often seen only on night dives is the lobster (Scyllarides latus), which has very short antennae, and the second antennae are reduced to form 2 shield shaped structures on each side of the head. It has relatively short walking legs and spined abdominal segments which can cause bad wounds if mishandled by divers. Its eyes are widely spaced on its broad head giving it a stubby appearance, colored brown green it blends well into its normal habitat among rocks and weed.
PRAWNS and SHRIMPS
Prawns and shrimps belong to the suborder (Natantia), and are decapods which swim, they have light exoskeletons and usually have laterally flattened bodies. One pair of antenna are distinctly larger than the other. They often have a prominent rostrum which is the main feature used in the identification of different species. Several species can be found in Turkey, and are particularly visible in torch light on night dives when they can be observed in almost every crevice and small cavern.
SPINY SPIDER CRABS (Maia squinado)
Spiny spider crabs are very common here but are difficult to find because they promote weed growth and other marine plants on their carapace which makes them blend perfectly with their habitat. Often the only time they can be detected is when they are mobile and what appears to be a part of the bottom weed moves. They have a spiny carapace and the front legs have small pincers. The spiny spider crab is a favorite prey of the common octopus, and their distinctive ovoid shaped ‘shells’, with very sharp spines along each side, can often be found littered around octopus habitats. Rarely exceeding 15cms from leg to leg in Turkish waters.
By contrast their cousins, the Giant Spider Crabs of Japan, are the largest of all crabs measuring up to 8 meters (27ft) leg to leg with claws 3 meters (10ft) apart. If you meet one in Turkey and survive, let us know.