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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 ...
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.
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 ...
The tubules are lined with a layer of cells that from puberty into old age, develop into sperm cells (also known as spermatozoa or male gametes). The developing sperm travel through the seminiferous tubules to the rete testis located in the mediastinum testis , to the efferent ducts , and then to the epididymides (depending on the species ...
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 rostrum is a greenish-blue, and the pleon is dark blue or black, with pinkish-grey or cream coloration on the margins (in some individuals the pleon is greenish-grey with pink speckles). The tail fan is cream-colored or pink around the outside margin.
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 ...
Rostrum (from Latin rostrum, meaning beak) is a term used in anatomy for several kinds of hard, beak-like structures projecting out from the head or mouth of an animal. Despite some visual similarity, many of these are phylogenetically unrelated structures in widely varying species.