Stenopus hispidus        

External Morphology

1)    The head

The head is made of five different segments. That includes two pairs of antennae, a mandible and two maxillae. The antennae are really elongated. Multisegmented appendages set out the body by a proximal segment of the antennular peduncle. An extension of the external margin of the antennular peduncle is observable in the form of an extended spine which is known as the stylocerite. The antennules are rather long. These appendages bear many olfactory sensilla or aesthetascs. The antennules are close to the head in an excavation named the antennular fossa. A pair of compound eye is present and is prominent on eye stalks. A rostrum is also present and really distinct. The cephalic skeleton, called the protocephalon, is in the ventral frontal region of the cephalothorax which promotes under the rostrum and takes in the eyes, antennules and both pair of antennae. A labrum, a fleshy triangular appendage, can be see just above the mouth part. The head also carry the mandibles, or jaws. The mandibles consist of two distinct regions: the molar and incisor process. A palp is present in between those two regions.

2)    The thorax

The thorax, or here cephalothorax is made of eight fused segments. Maxillipeds are the first three pairs of limbs. Second and third maxillipeds are quite pediform, the second maxilliped is composed of 5 segment and is used for feeding, handling and grooming, and the third maxilliped can be as big as or exceed the size of other thoracic appendages. The remaining five pairs of the thorax appendages are the walking legs or pereiopods. The carapace surround, enclose and protect the thoracic cavity where internal organs are found. The carapace carry a lot of spine like outgrowth.

3)    The abdomen

The abdomen is made of segmental arrangement of 6 segments called the pleura. The “tail” is composed of a pair of uropods which flank the telson. Both the uropods and the telson are armed with spines and setal arrangement. The abdomen also support the four biramous pair of swimming appendages called peleopods.