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Some claim insects evolved from prehistoric crustaceans, and they have secondary antennae like crustaceans, but not primary antennae. Antennae are the primary olfactory sensors of insects [7] and are accordingly well-equipped with a wide variety of sensilla (singular: sensillum). Paired, mobile, and segmented, they are located between the eyes ...
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 ...
The general shape of the antennae is also quite variable, but the first segment (the one attached to the head) is always called the scape, and the second segment is called the pedicel. The remaining antennal segments or flagellomeres are called the flagellum. [17]: 8–11 General insect antenna types are shown below:
Males are typically smaller than females, and in some species, such as Emerita rathbunae, the minute males live attached to the legs of the female. [7] Females are around 8–37 mm (0.31–1.46 in) in carapace length, depending on the species, while males vary from a similar size to females in E. austroafricana , down to 2.5 mm (0.098 in ...
The bodies of crustaceans are segmented; there is one ganglion (cluster of nerve cells) per segment. Each ganglion receives sensory and movement information via nerves coming from the muscles, body wall, and appendages such as walking legs, swimmerets and mouthparts. The ganglia show great functional autonomy; information received by the ...
These, like the maxillipeds of crustaceans, are modified legs and not true mouthparts. [2] The forcipules arise from the first body segment, curving forward and to the midline. The tip is a pointed fang, which has an opening from a venom gland. The forcipules are used to capture and envenomate prey.
Unlike many other crustaceans, the body is not clearly divided into segments. Most species have completely or partly lost their trunk segmentation, and there are no boundaries between the thorax and abdomen, and it has therefore been impossible to tell if the first pair of limbs after the maxillae belongs to the head or the thorax.
The long first antennae, two in number, are used by the males for gripping the females during mating. Afterwards, the female carries the eggs in two small sacs on her body. The larvae, or nauplii , are free-swimming and unsegmented.