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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:
In front of the pereiopods are three pairs of maxillipeds that function as feeding appendages. The head has five pairs of appendages, including mouthparts, antennae, and antennules. There are five more pairs of appendages on the abdomen. They are called pleopods. There is one final pair called uropods, which, with the telson, form the tail fan. [2]
For example, the Scarabaeidae have lamellate antennae that can be folded tightly for safety or spread openly for detecting odours or pheromones. The insect manages such actions by changes in blood pressure, by which it exploits elasticity in walls and membranes in the funicles, which are in effect erectile.
This has resulted in development in decapod crustaceans being generally abbreviated. [1] There are at most nine larval stages in decapods, as in krill, and both decapod nauplii and krill nauplii often lack mouthparts and survive on nutrients supplied in the egg yolk (lecithotrophy). In species with normal development, eggs are roughly 1% of the ...
Typically, each body segment carries one pair of appendages. An appendage which is modified to assist in feeding is known as a maxilliped or gnathopod. [citation needed] In annelids lateral protrusions from the body are called parapodia. In echinoderms an appendage called a pedicellaria is found. The end of the pedicellaria consists of valves ...
The first appendage pairs are elongated chelicerae, with the other five being biramous appendages. The exopods of these appendages bear setae on their tips, hence the name Setapedites. The opisthosoma is divided into a pre-abdomen and an abdomen. Each pre-abdomen segment has both a pair of appendages and on the tergites, leaf-shaped ...
The head is the largest part of the body, and bears four pairs of appendages. Two pairs of well-developed antennae are used to swim through the water. In addition, there are a pair of mandibles and a pair of maxillae. The thorax has three primary pairs of appendages. The first of these has different functions in different groups.
Natantia (Boas, 1880) is an obsolete taxon of decapod crustaceans, comprising those families that move predominantly by swimming – the shrimp (comprising Caridea and Procarididea), prawns (Dendrobranchiata) and boxer shrimp.