Agnatha

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Agnatha

• Jawless Fish

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• Kingdom Animalia
• Phylum Chordata
• Subphylum Vertebrata
• Class Agnatha
• (Jawless fish)

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Class Agnatha4 extinct orders, 1 living order

• Extinct
• Heterostraci
• Anapsida
• Osteostraci
• Extinct orders known collectively as the
  ostracoderms

• Living
• Cyclostoma
• Hagfish and lampreys

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Ostracoderms (extinct)600 species

• 440-360 million years ago
• Fish with bony armor and no jaws
• Cartilaginous skeleton
• 10-50 cm long

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Order Cyclostoma (living)

• Characteristics
• Cartilaginous skeleton
• No scales, jaws or paired fins
• External fertilization of eggs
• No specialized reproductive ducts
• Larva similar to Amphioxus

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Hagfishes60 species

• Pinkish-purple, elongate bodies
• No scales
• Gills are pouches, not slits
• 3 pairs of barbels around nostril and mouth
• Found in oceans world-wide (except polar regions)
  at depths of 25-600m

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Hagfishes

• Diet
• Burrow
• Scavenge
• Tie themselves in a knot,why?

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Hagfishes

• Slimed

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Eel skin wallets
No, they dont come from eels!
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Hagfishes

• Reproduction
• Very little is known
• Female lays 20-30 large eggs with hook-like
  structures
• Young are miniature adults
• 100 females for every male

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Lampreys40 species

• Elongate body
• Cartilaginous skeleton with vertebral structures
• Found throughout the world, mostly northern
  hemisphere

• Oral disc used to suck blood and juice from other
  fish
• Parasitic and non-parasitic species

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Lampreys

• Parasitic species
• Born in freshwater stream
• Adult stage lasts 2 years
• Anadromous--Once mature, migrate from streams to
  ocean (or large body of fresh water)
• Parasitize large fish
• Migrate back to freshwater stream to spawn

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Lampreys

• Non-parasitic species
• Adult stage lasts less than 6 months
• Do not migrate stay in freshwater streams
• Have poorly developed teeth
• Adults do not eat at all
• Grow to 20 cm long

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Lampreys

• Reproduction (same for all species)
• Spawn in shallow, gravel-bottomed riffle in late
  winter or early spring
• Build a rock nest 1m in diameter, 3cm deep
• 1000-260,000 eggs, hatch in 14-20 days
• Adults die after breeding once
• Tiny larvae drift along until they reach mud,
  burrow in with only heads sticking out to filter
  feed on invertebrates
• Change position now and then
• Become adults after 3-7 years, parasitic species
  head to sea

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Lampreys in West Virginia

• Ohio Lamprey (Ichthyomyzon bdellium)
• Mountain Brook Lamprey (Ichthyomyzon greeleyi)
• Silver Lamprey (Ichthyomyzon unicuspis)
• Least Brook Lamprey (Lampetra aepyptera)
• American Brook Lamprey (Lampetra appendix)
• parasitic

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The Great Lakes Lamprey Incident

• The Sea Lamprey (Petromyzon marinus) was native
  to the Atlantic coast
• But

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Vocabulary

• Dorso-ventrally flattened
• Ostracoderms
• Spawning
• Riffle
• Parasitic
• Barbels
• Anadromous

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Retention Party!

• 1. List the 8 steps of Classification starting
  with Kingdom.
• 2. What 5 things make-up a Chordate?
• 3. What 3 things make-up a Vertebrate?
• 4. Who is considered the Father of Taxonomy?
• 5. Are some lampreys anadromous?
• Bonus What are my childrens names?