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The coxal gland is thought to be homologous with the antennal gland of crustaceans. The gland consists of an end sac (saccule), a long duct (labyrinth) and a terminal bladder (reservoir). [2] There is generally only one pair (two in some spiders), and they open on the coxae of the walking legs [1] or at the base of the second antennae in the ...
A tripartite structure is recorded from near the antennae, consisting of elevated walls arranged in a semicircle (likely to enlarge the surface for an excretory organ as in modern crustaceans), a pore representing an opening of the “antennal gland” (the purpose of which is unknown) and a sickle-shaped furrow surrounding this pore.
In Crustacea, the saccate metanephridia are associated with the antennae and form the antennal gland. In freshwater crustacea, the saccate metanephridia are especially large due to their role in osmoregulation; crustacea must remove large amounts of water from the tissues, as the cells are hypertonic to the surrounding water.
Opioid peptides and opioid receptors occur naturally in crustaceans, and although it was concluded in 2005 "at present no certain conclusion can be drawn", [3] more recent considerations suggest their presence along with related physiological and behavioural responses as indicating that crustaceans may experience pain.
However, careful control is required because physiological changes can occur due to noxious, but non-pain related events, e.g. cardiac and respiratory activity in crustaceans is highly sensitive and responds to changes in water level, various chemicals and activity during aggressive encounters.
The decapod (crustaceans such as a crab, lobster, shrimp or prawn) is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon . [1] [2] Each segment may possess one pair of appendages, although in various groups these may be reduced or missing. They are, from head to tail:
An ionocyte (formerly called a chloride cell) is a mitochondrion-rich cell within ionoregulatory organs of animals, such as teleost fish gill, insect Malpighian tubules, crustacean gills, antennal glands and maxillary glands, and copepod Crusalis organs. [1]
Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are a part of the subphylum Crustacea (/ k r ə ˈ s t eɪ ʃ ə /), a large, diverse group of mainly aquatic arthropods including decapods (shrimps, prawns, crabs, lobsters and crayfish), seed shrimp, branchiopods, fish lice, krill, remipedes, isopods ...