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The
Diversity of The World of Life
Vertebrates
(Vertebrata)
Lampreys
(Hyperoartia)
Representatives
Lampreys
Biology
APPROXIMATE
NUMBER OF KNOWN SPECIES WORLDWIDE
50
ENVIRONMENTS
Lampreys
live in freshwater and/or saltwater.
DESCRIPTION
The streamlined, eel-like body of lampreys bears slimy,
scale-less skin; no paired side fins; seven gill slits; and a sucking mouth, with horny teeth and a rasping tongue.
The body is reinforced by a "notochord" (a spine composed of
rubbery cartilage, not bone) with rudimentary vertebrae on either side and
with a small, cartilaginous "cranium" (braincase) behind the
mouth (Compare hagfish, with
which they were previously grouped).
FEEDING HABITS
Although they sometimes prey on invertebrates, lampreys are
typically parasitic, using their sucking, rasping mouth to attach
themselves onto the body of other fish and drink their blood.
Lampreys are serious pests of game fish in North America.
RESPIRATION
Dissolved
gases diffuse from water passed over the gills, on either side of the
front of the body, and into the pharynx (throat) modified into a
"breathing tube", isolated from the esophagus (food passage), so
that the animal can "breathe" while its mouth is attached to the
body of its host.
COORDINATION
Like
various fossil jawless fish
but unlike any other modern vertebrates, lampreys have a single nostril on
the upperside of the head. However, this nostril is not used for
breathing; rather, it allows for the entry of water past the internal
organ of smell. The brain, within the cartilaginous braincase, is
small. Also like prehistoric ostracoderms,
lampreys have a single, primitive "pineal eye" atop the head,
which can sense light but not resolve images.
REPRODUCTION
The
eggs of lampreys are typically laid in streambed nests and are externally
fertilized (by free-swimming sperms). The adults typically die after
spawning. Young lampreys are "larvae", unlike the
adults: They have no suckers; rather, they feed by catching food
with strands of mucous.
Vertebrates
(Vertebrata)
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