Body Parts of a Shrimp Tadpole

The tadpole shrimp is a crustacean that lives in temporary bodies of fresh water. It is also known as "triops," which is Greek for three eyes. The tadpole shrimp is considered a living fossil and has survived for millions of years, dating back to the Triassic Age. It lives on all continents except Antarctica and has a life span of between 20 and 90 days. Its body consists of a head and a trunk mostly covered by a carapace.

  1. Carapace

    • The carapace is a posterior fold or back cover of the crustacean body wall. It covers the back of the head and part of the thorax. Most people tend to confuse carapace with cephalothorax, the anatomical name for the first body part of arachnids and some crustaceans. But a carapace is not a cephalothorax, as no thoracic segment is fused with the head.

    Head

    • The tadpole's head is composed of five fused segments. On the back side are three eyes: two compound eyes, which consist of thousands of individual photoreception units, and one naupilar eye that does not see images, but may have a lens and sense the direction of light.

      On the ventral or front part, it has a lens-like window that leads light to the naupilar eye, appendages called antennaes and strong mandibles with brownish-yellow teeth.

    Thorax

    • It is not generally established where the thorax ends and where the trunk begins. Some experts believe that the thorax consists of 11 segments. Each segment has a pair of appendages called thoracopods. The first thoracopod functions as a sensory structure. On the 11th thoracopod pair, the female tadpole carries her egg sacs until she is ready to lay them in water.

    Trunk

    • The trunk is a series of between 16 and 25 fused segments. The six fused segments that follow the 11 segments of the thorax, each containing a pair of appendages, are part of the trunk, according to some experts, or of the thorax, according to others. Following these six segments are other fused segments that do not have appendages.

    Internal Anatomy

    • The tadpole's heart is located in the first 11 segments of the thorax and is a long dorsal tube. The mouth is connected by an esophagus to the stomach, which is located in its head. The intestines extend through the trunk to a rectum that opens at the anus. The maxillary glands are the excretory organs.