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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.
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 ...
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.
The classical view was that the chelicerae were homologous to the second antennae of crustaceans (i.e., they are innervated from the tritocerebrum), a view based partly on the fact that the chelicerae were innervated from the same ganglion that innervates the labrum, which is the tritocerebrum in crustaceans and insects.
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]
Johnston's organ detects motion in the flagellum (third and typically final antennal segment). It consists of scolopidia arrayed in a bowl shape, each of which contains a mechanosensory chordotonal neuron. [3] [4] The number of scolopidia varies between species.
Diagram of the primary components of a chordotonal organ scolopidium. Chordotonal organs can be composed of a single scolopidium with only a single sensory, bipolar neuron (such as the tympanal ear of a notodontid moth), or up to several thousand scolopidia, each equipped with up to four sensory neurons (as in the mosquito Johnston's organ). [6]
In terrestrial pulmonate gastropods, eye spots are present at the tips of the tentacles in the Stylommatophora or at the base of the tentacles in the Basommatophora.These eye spots range from simple ocelli that cannot project an image (simply distinguishing light and dark), to more complex pit and even lens eyes. [6]