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Coxal gland and its components. The coxal gland is a gland found in some arthropods, for collecting and excreting urine. They are found in all arachnids (with the exception of some Acari), and in other chelicerates, such as horseshoe crabs. [1] The coxal gland is thought to be homologous with the antennal gland of crustaceans.
Antennae (sg.: antenna) (sometimes referred to as "feelers") are paired appendages used for sensing in arthropods. Antennae are connected to the first one or two segments of the arthropod head. They vary widely in form but are always made of one or more jointed segments.
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.
If crustaceans feel pain, there are ethical and animal welfare implications including the consequences of exposure to pollutants, and practices involving commercial and recreational fishing, aquaculture, food preparation and for crustaceans used in scientific research.
Eyestalk ablation is the removal of one (unilateral) or both (bilateral) eyestalks from a crustacean. It is routinely practiced on female shrimps (or female prawns) in almost every marine shrimp maturation or reproduction facility in the world, both research and commercial .
Nitrogenous waste is excreted through glands on the maxillae, antennae, or both. [17] The primary sense of ostracods is likely touch, as they have several sensitive hairs on their bodies and appendages. Compound eyes are only found in Myodocopina within the Myodocopa. [23] The order Halocyprida in the same subclass is eyeless. [24]
8 - nerve of the eye: Drawing of cross sections of the extracted tentacle (left) and constricted tentacle (right) with and eye of Helix pomatia. 1 - nerve of an eye 2 - 3 - 4 - eye 5 - tentacle ganglion 6 - epidermis 7 - 8 - nerve of an tentacle 9 - retractor muscle 10 - Well-developed lens eye of Eustrombus gigas on eyestalk has a black iris.
Compared with simple eyes, compound eyes possess very large view angles and better acuity than the insect's dorsal ocelli, but some stemmatal (= larval eyes), for example, those of sawfly larvae (Tenthredinidae) with an acuity of 4 degrees and very high polarization sensitivity, match the performance of compound eyes.