Advertisement Upgrade to remove ads


Organisms that lack a backbone


Invertebrates with jointed appendages


External skeleton


A substance that is chemically similar to cellulose or starch


Scientists who study insects


A profound change in form from one stage to the next in the life history of an organsim, as from the caterpiller to the pupa and from the pupa to the adult butterfly


The immature form of these insects that do not pass through a pupal stage. Nymphs usually resemble the adults, but are similar, lack fully developed wings, and are sexually immature

Compound Eye

An arthropods eye is subdivided into many individual, light receptive elements, each including a leens, a transmitting apparatus, and retinal cells


The anterior part of the body in certain arachnids and crustaceans, consisting of the coalesced head and thorax


Either of the first pair of fanglike appandages near the mouth of an arachnid, such as a spider, often modified for grasping and piercing


One of the second pair of appendages near the mouth of a spider or other arachnid that are modified for various reproductive, predatory, or sensory functions

Book Lungs

A saccular respiratory organ found in some arachnids, such as scorpions and spiders, consisting of several parallel membranous folds arranged like the pages in a book


One of the small opeenings in the back part of a spider or silk-producing insect larva, through which the sticky fluid that dries into silk is released


A bony or chitinous shield, test, or shell covering some or all of the dorsal parts of an animal as of a turtle


One of the three pairs of crustaceans head appendages located just posterior to the maxillae and used in feeding


One of the paired abdomial appendages of certain aquatic crustaceans, such as shrimp, lobsters, and isopods, that functions primarily for carrying the eggs in females and are usually adapted for swimming. Also called pleopod

Green Glands

One of the pair of excretory organs in each side of the head region of decapod crustaceans, emptying at the base of the antennae

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording