Transcript Jawless Fish Phylum - MATES-Biology-I

Jawless Fish
Phylum: Chordata
Sub-Phylum: Vertebrata
Class: Agnatha
• There are two primary marine types of the class
Agnatha. They are Hagfish and Lampreys.
• Most Primitive living fishes
• Hagfish are of the order, Myxiniform. They are
related to the slimefish. They have the peculiar
habit of tying themselves into knots in order to
shed their slime coat and make a new one.
Hagfishes
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20 known species
Deep, cold waters
2.6 ft.
Skin is used for leather goods
Hagfish
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feed on polychaete worms, shrimp, and dead or dying fish
attach to fish, form a knot in the tail and pass it forward to rip off
flesh. Image © BIODIDAC.
usually enter coelomic cavity and feed on soft parts
• many mucous glands present for antipredator defense
Lampreys
http://itech.pjc.edu/jwooters/zoology/virtual_review/lamprey.htm
• Lampreys are of the
order,
Petromyzontiform.
They are suckers and
attach themselves to
fish in order to
parasitize off them.
• Found in Freshwater
• 30 species
Sea Lamprey Life Cycle
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A. Sea lampreys go through an extended larval phase before metamorphosing into the
bloodsucking parasitic phase. Each summer and fall there is one group of parasitic sea lampreys
actively feeding in the Great Lakes.
B. The next spring, that group leaves the lake and migrates into tributary streams where they must
build nests in clean gravel with flowing water.
C. Each female spawns an average of 60 to 70 thousand eggs.
D. After hatch, the larvae drift downstream to areas with slower currents and sand/silt bottoms.
There, they establish permanent burrows and enter a larval stage varying in duration from 3 to 10ormore years.
E. Larvae lack eyes and the oral disc. Living concealed in their burrows, they are harmless and
filter microscopic material from the water for food. When they reach lengths of 120 mm or more,
some individuals begin metamorphosis in mid summer.
F. During metamorphosis they develop eyes, the oral disc, and changes in their kidneys that (in
their native range) would allow them to enter the salt water of the Atlantic Ocean. That fall or the
following spring, they instead enter the Great Lakes to feed parasitically on fish that summer and
fall, and mature and spawn the next spring—completing their life cycle. Sea lampreys only spawn
once and then die after spawning.
Lamprey on a Salmon
Lamprey Anatomy
D-eel-icious, if you appreciate an
earthiness
• So what does lamprey taste like? "I
would have to say it tastes like
lamprey," says Chef Bob Bennett,
"because it does not have a flavor that
you can associate with anything else."
Critical Thinking???
Discuss this with your partner(s)
• Hagfishes have tiny eyes buried beneath
the skin and lampreys have large,
exposed eyes. Explain how each type of
eye is an adaptation for feeding style.
Critical Thinking???
Discuss this with your partner(s)
• How & why would the
respiration process
differ from a lamprey
to a bony fish?
Interpret This Graph