Spelaeogriphaceans: Spelaeogriphacea

Spelaeogriphaceans (speh-lee-oh-grih-FAY-see-ans) are blind with long, cylinder-shaped bodies. Adults measure from 0.12 to 0.28 inches (3.1 to 7.2 millimeters) and have three distinct body regions: head, thorax, and abdomen. The head has a distinct, beaklike projection called the rostrum. Both pairs of antennae are long and branched, or biramous (BY-ray-mus). The eyestalks are present, but the eyes are not. The jaws, or mandibles, are uniramous (YU-neh-RAY-mus) or unbranched. A short, shieldlike carapace covers the back of the head and the first two segments of the segmented thorax. The first thoracic segment is firmly attached, or fused, to both the head and the carapace. There is one pair of maxillipeds, thoracic limbs that work together with the mouthparts.

The remaining pairs of thoracic limbs are called pereopods (PAIR-ee-oh-pawds). The pereopods are used for walking and are also used to move oxygen-carrying water past the body. The abdomen has six segments. Each of the first five segments of the abdomen has a pair of biramous limbs called pleopods (PLEE-oh-pawds). The first four pairs of pleopods are well developed and paddlelike; the fifth pair is very small. At the end of the abdomen is a pair of slender biramous appendages called the uropods (YUR-oh-pawds). In between the uropods is a slender, taillike segment called the telson. The telson is not tightly joined with, or fused to, the last abdominal segment. The telson and uropods do not join together to form a fanlike tail.