Leptostracan Morphology

...a look with the scanning electron microscope

CONTENTS

Rostrum Eye Antennule Antenna

Carapace Abdomen Telson

Thoracopods Pleopods Caudal furcae

The rostrum of leptostracans is essentially a flap of cuticle that articulates with the carapace at the anterior (front) end of the animal.

The eyestalks of leptostracans vary considerably from one genus to the next. In fact, the leptostracan eye is perhaps the most notably variable character. In the genus Nebalia, the eye is relatively simple, and it is usually as long or shorter than the rostrum. In

Antennule

Antenna

Unlike the carapace of a crab, the carapace of all leptostracans is folded around the body. Superficially, this gives the animal a bivalved appearance similar to that of other crustaceans such as clam shrimps and ostracodes. However, in these other taxa, the carapace actually consists of two valves (the two sides) that are connected by a hinge. In the Leptostraca, the carapace is continuous and unhinged...much like an upside-down taco.

Abdomen

Telson

The limbs that arise from the thorax in Crustacea are called pereopods or thoracopods. Leptostracans possess 8 thoracopods.

The pleopods are those limbs that arise from the abdomen. All leptostracans possess 6 pairs of pleopods. The first pleopod arises from the first abdominal segment (pleonite), the second pair from the second abdominal segment, and so on. The last two pairs of pleopods (the fifth and sixth pair) are considerably smaller than the first four, consisting only of two (and in several cases, one) segments.

The caudal furcae are the posteriormost appendages of the leptostracan. These single-segmented appendages arise from the telson. They are generally long and narrow and bear multiple rows of setae.