Mantis Shrimps: Stomatopoda

Typical mantis shrimps have long bodies that are cylinder-shaped or slightly flattened from top to bottom. They vary considerably in color, depending on the species or the individual. Some are brightly colored, while others are marked so that they blend in with their surroundings. At the front of the head are moveable segments that bear the eyestalks and two pairs of antennae. The antennae are sensitive to odors and disturbances in the water.

Mantis shrimps have the most highly developed eyes of all crustaceans, and their vision is excellent. Each compound eye is made up of multiple lenses. The eyes are often iridescent, appearing like jewels, and are mounted on the end of a periscope-like stalk to give them a clear view in all directions. A specialized band of lenses across each eye is unique and divides the eyes into three distinct visual regions. Mantis shrimps have the ability to see shapes accurately under all light conditions and to gauge distances, allowing them to use their lightning-quick raptorial limbs with deadly accuracy. The middle band of lenses is used to see infrared, visible, and ultraviolet light. The other two regions can see polarized light. Polarized light travels in parallel planes. Parts of the antennae and tails of mantis shrimps reflect polarized light and may provide them with the ability to locate and communicate with one another.

A shieldlike carapace (CARE-eh-pes) covers the thorax or midbody, and the abdomen is distinctly segmented. The thorax has eight pairs of limbs. The first five pairs, the maxillipeds (mack-SIH-leh-pehds), are associated with the mouth and are used for prey capture and eating. The second pair of maxillipeds is very conspicuous and resembles the front legs of a praying mantis. They are called grabbing, or raptorial (rap-TORE-ee-all), limbs and are used to stab or club prey. When not in use, they are kept folded like jack knives under the head and body. Mantis shrimps can replace lost or damaged raptorial limbs. Damaged limbs are forcibly removed with the other maxillipeds. The lost limb is replaced with the next molt and grows to full size after three more molts. Three more pairs of maxillipeds follow the raptorial limbs. The remaining three pairs of thoracic midbody limbs are used for walking.

The abdomen has five pairs of leaflike limbs called pleopods (PLEE-oh-pawds). They are used for swimming and also have gills for breathing. The abdomen ends in a large, fanlike tail made up of the flat tail segment, and a pair of appendages, or uropods (YUR-oh-pawds).

Male and female mantis shrimps are easily distinguished. Males have a pair of long, slender sperm-transferral organs located at the bases of the last pair of walking legs. The female's reproductive organs appear as a narrow slit that opens underneath the body between the first pair of walking legs. In some species the males have larger bodies than the females, with larger raptorial limbs and tails.