Pentastomida (tongue worms)

PENTASTOMIDA HAVE/ARE

PENTASTOMIDA DON'T HAVE

Greek: pente = five; stoma = mouth

Pentastomida are the tongue worms. There are about 100 described species; all are parasitic, and range in length from 2 - 16 cm. Their main host is usually a reptile, where they live in the lungs and nasal passages (see Cephalobaena tetrapoda below). One species lives in the air sacs of terns, and another in the nasopharyngeal region of cats, dogs and just occasionally humans.

On the right is Lingutula serrata, the tongue worm. Many Pentastomida have an intermediate host which can be a fish, reptile or most commonly, small herbivorous mammals, e.g. rabbits. These intermediate hosts are then eaten by the primary host. Man can also be a host to the larval, or intermediate stage.

In the adult form there are usually five protuberances at the anterior end; four of these bear claws, and the fifth bears the mouth and two attachment hooks (see right). The adults live with the front (hooked) end deeply embedded in the host tissue and feed off the blood, mucus or lymph.

The sexes are separate, and the female can produce millions of eggs increasing her size almost 100-fold. The eggs are swallowed by the host and then excreted with the faeces. The larvae have three, and later two, pairs of legs and a tail.