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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.
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.
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]
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.
Although composed of over 16,000 cells, [6] the Drosophila compound eye is a simple repetitive pattern of 700 to 750 ommatidia, [7] initiated in the larval eye imaginal disc. Each ommatidium consists of 14 neighboring cells: 8 photoreceptor neurons in the core, 4 non-neuronal cone cells and 2 primary pigment cells. [ 6 ]
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.
Compound eye of a house centipede Compound eye of a dragonfly. A compound eye is a visual organ found in arthropods such as insects and crustaceans.It may consist of thousands of ommatidia, [1] which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distinguish brightness and color.
Copepods (/ ˈ k oʊ p ə p ɒ d /; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat.Some species are planktonic (living in the water column), some are benthic (living on the sediments), several species have parasitic phases, and some continental species may live in limnoterrestrial habitats and other wet terrestrial places, such as ...