Biomedical Engineering Reference
In-Depth Information
Nematoda (Chapter 27)
Arthropoda
Chelicerata (Chapter 29)
Hexapoda (Chapter 30)
Crustacea (Chapter 31)
Platyzoa
Platyhelminthes (Chapter 26)
Acanthocephala (Chapter 28)
Fungi (Chapters 33
37)
From the human point of view, Class Craniata is the most fascinating group
of organisms on earth, because it includes ourselves. The most distinctive evo-
lutionary characteristic of Class Craniata is the neural crest. In embryologic
development, the neural crest derives from a specialized compartment of cells
lying between the ectoderm and the primitive neural tube. The neural
crest gives rise to the peripheral nervous system, to the connective tissue of
the cranium, to several endocrine glands, and to the connective tissue compo-
nent of the teeth. As a general rule, if an animal has something that we might
recognize as a face, it is a member of Class Craniata.
Although members of Class Craniata contain some of the most intelligent
and predatory species on the planet, virtually no members of the class are
infectious in humans. Basically, the members of Class Craniata enjoy eating
one another, but they seldom infect one another. In the case of human infec-
tions, there is one exception: Trichomycteridae plectrochilus, the toothpick
catfish.
Craniata
Actinopterygii
Siluriformes
Loricarioidea
*Trichomycteridae
The toothpick catfish, also known as candiru, is a small fish, shaped like an
eel, about an inch in length, that lives in the Amazon and Oronoco Rivers.
The candiru normally infects riverine fish, inserting itself between the gills,
attaching to tissue with the aid of barbs, and feeding off the host's blood
(hematophagy). There are a few case reports, and many anecdotal accounts, of
candiru entering the urethra, the vagina, or the anus, of swimming or wading
humans. Removal of the fish may require surgical excision.
Infectious species:
Trichomycteridae plectrochilus, candiru, toothpick fish, parasitic catfish
of the Amazon (candiru disease)
