Download Class Cephalaspidomorphi Classification

Class Cephalaspidomorphi
Classification
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Composed of fish that lack true fins, jaws, and bones
Three types
o Osteostracans- prehistoric bone-armored fish
o Anaspids- lamprey ancestors
o Lampreys- the only living Cephalaspidomorphi
Note: All that we know of this class comes from the study of lampreys since they are the only living
descendents. Because of this, all other information about the class is specific to lampreys and is considered to
be true of the now extinct species that also make up this class.
Habitat
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Young lampreys live either in muddy bank of a river or lake, or in the sandy banks of the
sea.
Adult lampreys live in open water in either an ocean or a lake.
Feeding Mechanisms
 Lamprey’s have no actual jaw. Instead, they rely on 11-12 rows of teeth arranged in a
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circular pattern around the mouth. This arrangement is known as a buccal funnel.
To feed, a lamprey grabs onto the side of its prey with its outer teeth while using its inner
ones and its tongue to create a hole. Enzymes are secreted to prevent platelets from
forming a clot in the host’s blood.
A lamprey lacks a stomach, and must constantly suck the blood of their host to survive.
The host will eventually die from the loss of blood, at which time the lamprey must seek
out a new host.
Lamprey larva feed on microorganisms in the streams they spawn in and only become
parasitic after reaching adulthood.
Reproduction
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Lamprey’s reproduce in the freshwater streams in which they spawned. Males build nests
out of the rocks in the stream for the females to lay their eggs.
Lamprey’s reproduce externally. Once the female has laid her eggs, the male must
fertilize them.
Unique Characteristics
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Lampreys are vertebrates; however their bone structure is different from other vertebrates.
They lack almost every bone found in other vertebrates and have bones made entirely
from cartilage.
Unlike most fish, lampreys have no fins.
Lampreys have a different type of gill than most fish. Instead of having slits for water to
pass through, lampreys have pouches that are open on the outside, allowing water to pass
over them.
Lampreys are cold-blooded.
Despite being parasitic, lampreys are considered to be beneficial. Their migration to and
from spawning grounds allows nutrients from the ocean or lake to be shared with the
steam. Also, the nest building process of lampreys stirs up nutrients trapped in the silt.
Sources
http://scienceblogs.com
http://www.untamedscience.com
http://animals.jrank.org
http://ua.dnr.wi.gov
http://en.wikipedia.org/wiki/Lampreys
http://en.wikipedia.org/wiki/Cephalaspidomorphi