Crayfish Diagram Unlabeled – External Anatomy to Fill In

All 12 parts on the diagram

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Start here: 7 main parts 7

Cephalothorax The front of the two main body parts. Head and thorax joined, carrying the eyes, antennae, mouthparts and legs.
Carapace The shell covering the cephalothorax, protecting the internal organs and the gills.
Antennae The long feelers on the head, the second pair of head appendages.
Chelipeds Legs armed with a claw, called a chela. On this crayfish they are the big front pair.
Walking legs The legs behind the claws, used mainly for walking and gathering food. With the chelipeds they make the ten legs of a decapod.
Abdomen The back of the two main body parts, made of segments.
Telson The central plate at the end of the abdomen. Part of the tail fan.

The front: 6 3

Rostrum Part of the carapace that sticks out in front of the eyes.
Compound eyes The eyes, usually on stalks, on the head.
Antennules The short first pair of head appendages, each forked in two.

The tail: 4 2

Swimmerets Small legs under the abdomen. Used mainly for swimming and, in females, for carrying eggs.
Uropods The paired side plates of the tail fan. With the telson they steer while swimming and power the quick backward escape.

How this list was compiled: Read 2026-09-26. Wikipedia, Decapod anatomy, https://en.wikipedia.org/wiki/Decapod_anatomy : the body in two main parts, the cephalothorax and the pleon (abdomen), of segments with paired appendages; the head's antennules, antennae, mouthparts and usually stalked compound eyes; the pereiopods as walking legs used also to gather food, the ten legs of a decapod, those with a claw (chela) called chelipeds; the carapace covering the cephalothorax and protecting the organs and gills, its part projecting in front of the eyes called the rostrum; the pleopods (swimmerets) as swimming legs also used to brood eggs; the tail fan of paired uropods and the telson, used for steering and the escape reaction. Licence: own work

The drawing: Drawn for this site by script, 2026-09-26. Own work, nothing traced. Licence: own work

How it works

A crayfish diagram with no labels, seen from above with the feelers at the top of the sheet and the tail fan at the bottom. Twelve lines lead off the animal, each with room for one name.

Read the full guide

Crayfish diagram, no labels: twelve names

Head to tail: antennae, antennules, rostrum, compound eyes, carapace, cephalothorax, chelipeds, walking legs, abdomen, swimmerets, uropods and telson. Parts that come in pairs get one line, so the two chelipeds share a name and so do the eight walking legs.

Two lines to the front half

The line that stops on the rim of the shell is the carapace, the shell itself. The line that reaches the middle is the cephalothorax: the body under that shell, head and thorax joined.

At the tail fan, the telson is the single middle plate and the uropods are the plates on either side of it.

Questions and answers

Which are the antennae and which are the antennules?

The antennules are the first pair of head appendages and the antennae the second. On this sheet the antennules are the short forked pair and the antennae the two long curving feelers.

Where are the swimmerets on a crayfish diagram?

Under the abdomen. From above only their ends show, as the small paddles along each side of the tail segments, and one line reaches the first of them.

Does the diagram show the underside of the crayfish?

No, only the view from above. The mouthparts and the gills under the carapace are not drawn, and no line asks for them.

Is there an answer key for the crayfish diagram?

Yes: the same crayfish with a name at the end of each line. Swimmerets and walking legs are the everyday names; a textbook may print pleopods and pereiopods.