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Pontastacus leptodactylus, [2] the Danube crayfish, [3] Galician crayfish, [3] Turkish crayfish [4] or narrow-clawed crayfish, is a relatively large and economically important species of crayfish native to fresh and brackish waters in eastern Europe and western Asia, mainly in the Pontic–Caspian region, among others including the basins of the Black Sea, and the Danube, Dnieper, Don and ...
Compared to other species of crayfish in its range, L. chimera is a sizable crayfish. On average, adults of this species range from about 9.5 to 11.8 centimeters (or 3.7 to 4.7 inches) in body length, measuring from the anterior tip of the rostrum to the posterior tip of the telson.
Pigment cells are located at an ommatidium's vertices, thus each pigment cell lines the outside of three mutually-adjacent ommatidia. Light entering at an angle passes through the thin cross-section of the photoreceptor cell, with only a tiny chance of exciting it, and is absorbed by the pigment cell, before it can enter a neighboring ommatidium.
Austropotamobius torrentium, also called the stone crayfish, is a European species of freshwater crayfish in the family Astacidae. It is mostly found in tributaries of the Danube , having originated in the northern part of the Balkan Peninsula .
The Dougherty Plain cave crayfish grows to a length of about 53 millimetres (2.1 in) with antennae twice this length. It is a colourless species with unpigmented eyes, segmented cephalothorax and abdomen, a pair of slender chelae (claws) with a row or two of tubercles and long slender appendages. The rostrum is long and unadorned with tubercles ...
The rostrum is very prominent and contains 11 to 14 dorsal teeth and 8 to 11 ventral teeth. The first pair of walking legs ( pereiopods ) is elongated and very thin, ending in delicate claws ( chelipeds ), which are used as feeding appendages.
One of the brain areas that receives primary input from the lateral line organ, the medial octavolateral nucleus, has a cerebellum-like structure, with granule cells and parallel fibers. In electrosensitive fish, the input from the electrosensory system goes to the dorsal octavolateral nucleus, which also has a cerebellum-like structure.
The region rostral to the cephalic groove, which separates the head and thorax region, is characterized by the presence of eyes, antennae and claws while the region caudal contains four pairs of walking legs. This is the crayfish's primary mode of locomotion. [2] [3] The abdominal section of the crayfish is divided into seven segments. These ...