Crustaceans

Pentastomes

Armillifer armillatus
Adults of Armillifer armillatus in a Chinese Viper lung. Nymphal stages of this tongue worm occur in the inner organs and musculature of a variety of species including humans and rodents. The calcification of encysted nymphs are often observed in radiographs.

Linguatula serrata
Female (top) and male Linguatula serrata, commonly referred to as 'tongue worms'. Linguatula serrata adults primarily live in the nasal passages of canids, but may also be found in humans, horses, and ungulates. Pathogenesis is similar to that of the nasal bot, with irritation and nasal discharge being the greatest clinical signs. ​

Linguatula serrata
Transverse section of the nasal cavity of a dog revealing a Linguatula serrata dorsal to the hard palate in the ventral nasal meatus. Adult pentastomes are most often found in carnivorous reptiles, but may be found in a diverse array of other vertebrates.

Pentastomid
A pentastomid egg found on fecal flotation. Eggs of are large, measuring over 100 μm, and are often surrounded by a capsule. Note that legs bearing hooklets are visible on the larva within the egg. Ingestion of these eggs is the source of infection for intermediate hosts.

Pentastomid
Removed from the lungs of a Gaboon viper (Bitis gabonica), this pentastomid is suspected to be Armillifer armillatus. There are at least 130 species of pentastomids. All are obligate parasites of vertebrates and adults are found in the respiratory tract.

Pentastomid
Pentastome nymphs in a fish. Most human cases of porocephalosis (a generic term implying any pentastome infection) are a result of the ingestion of undercooked fish

Porocephalus crotali
Nymphs of Porocephalus crotali in the mesenteric lymph nodes, omentum, liver, subserosa of the small and large intestines, mesentery, and lungs of a dog. Nymphal development of pentastomes occurs in the intermediate host.