Superclass Agnatha (Cyclostomata)
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Questions and Answers

What is the primary reason hagfishes are known as slime eels?

  • They inhabit both fresh and marine waters.
  • They produce a large amount of slime for protection against predators. (correct)
  • Their bodies are shaped like eels.
  • They have a unique method of locomotion.

Which of the following characteristics is NOT true about hagfishes?

  • They primarily feed on marine invertebrates.
  • They have a terminal mouth.
  • They possess gill slits.
  • They have a larval stage. (correct)

Where do fresh water lampreys typically lay their eggs?

  • In fresh water. (correct)
  • In brackish water.
  • In marine environments.
  • In cold seawater depths.

What distinguishes the feeding habits of hagfishes?

<p>They often bore into fish to eat them from the inside. (C)</p> Signup and view all the answers

Which of the following descriptions is accurate regarding the habitat of hagfishes?

<p>They are found in cold seawater and often lie buried in soft bottoms. (D)</p> Signup and view all the answers

What is a defining characteristic of Cyclostomata?

<p>They are the only living vertebrates without true jaws. (D)</p> Signup and view all the answers

Which of the following accurately describes the circulatory system of Cyclostomata?

<p>It is closed and has a two-chambered heart. (B)</p> Signup and view all the answers

What feeding behavior do hagfish exhibit?

<p>They are predators, feeding on fish blood and tissue. (D)</p> Signup and view all the answers

How many gill openings do Cyclostomata typically have?

<p>6-14 pairs (C)</p> Signup and view all the answers

What type of skeleton do Cyclostomata possess?

<p>Cartilaginous skeleton without bones. (D)</p> Signup and view all the answers

Which of the following is a feature of the lamprey's morphology?

<p>A round mouth with many horny teeth. (C)</p> Signup and view all the answers

What is the primary reproductive characteristic of hagfish?

<p>They possess separate sexes. (A)</p> Signup and view all the answers

Which statement about the respiratory structure of Cyclostomata is true?

<p>They breathe through gills with multiple openings. (B)</p> Signup and view all the answers

Flashcards

Agnatha (Cyclostomata)

Superclass of jawless fish, including lampreys and hagfish, characterized by their lack of jaws, round mouths with teeth and suckers, and cartilaginous skeletons.

Cephalaspidomorphi

The class of jawless fish that includes lampreys, known for their parasitic nature and feeding on fish blood and tissue.

Pteraspidomorphi

The class of jawless fish that includes hagfish, known for their slimy bodies and scavenging lifestyle in the ocean.

Hyperoartia

The subclass that contains lampreys, known for their parasitic lifestyle, round mouths with teeth, and dorsal fins.

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Hyperotreti

The subclass that contains hagfish, known for their slimy bodies, scavenging lifestyle, and lack of distinct fins.

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Agnatha Respiration

The respiratory system of Agnatha, which utilizes gills for breathing, and has 6-14 pairs of gill openings.

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Agnatha Circulation

The circulatory system of Agnatha, characterized by a closed system with a two-chambered heart.

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Agnatha Digestion

The digestive system of Agnatha, which includes a mouth with teeth and a sucker, pharynx, intestines, and accessory organs like pancreas and liver.

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Larval stage

A larval stage is a distinct developmental phase in an animal's life cycle that occurs before it becomes an adult. During this stage, the organism undergoes significant physical and physiological changes.

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Lampreys

Lampreys are eel-shaped fish that have a cartilaginous skeleton and a unique feeding mechanism. They are mostly found in freshwater habitats and some species migrate to saltwater to reproduce.

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Hagfish

Hagfish are primitive, jawless fish that live in the deep ocean. They are known for their slime-secreting defense mechanism and are frequently called slime eels.

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Direct development in Hagfish

Hagfish have a direct development, meaning they do not have a larval phase. Their development is continuous and they hatch as miniature versions of the adult.

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Slime defense in Hagfish

Hagfish secrete a large amount of slime to deter predators. This slime is a sticky and viscous substance that makes them difficult to catch and can even clog the gills of attackers.

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Study Notes

Superclass Agnatha (Cyclostomata)

  • Agnatha (Cyclostomata) evolved around 500 million years ago
  • Once a large group, now many are extinct, except for lampreys and hagfish
  • Found in deep marine waters of tropical seas and shallow temperate zones
  • Primarily parasitic, feeding on fish as adults
  • Resemble eels
  • Lack true jaws, hence the name Agnatha

Agnatha Classification

  • Class Cephalaspidomorphi - Hyperoartia - Lampreys:

    • Found in both marine and freshwater environments
    • Predatory, feeding on fish blood and tissue
    • Have a ventral mouth with numerous horny teeth
    • Nostrils are located dorsally
    • Possess a well-developed dorsal fin
    • Development is indirect; they have a larval stage
  • Class Pteraspidomorphi - Hyperotreti (Myxiniformes) - Hagfish:

    • Exclusively marine, found in cold seawater at depths up to 1300 meters
    • Live on soft bottoms, in burrows
    • Feed on invertebrates, dead or crippled fish
    • May bore into fish bodies
    • Lack a buccal cavity
    • Terminal nostrils
    • 6-14 pairs of gill slits
    • Eggs are few and large
    • May lack or have weak dorsal fins
    • Direct development (no larval stage)

Agnatha Characteristics

  • Body is round and elongated, resembling an eel
  • Mouth has rows of teeth and suckers
  • Endoskeleton is cartilaginous, with a notochord throughout their lives
  • Odd fins (dorsal and caudal), but lack paired fins
  • Soft, smooth skin without scales
  • Respiration through gills, with 6-14 pairs of gill openings
  • Heart is two-chambered
  • Digestive system includes teeth, a sucker, pharynx, intestines, stomach, pancreas, liver and gallbladder, opening into intestines and anus
  • Paired mesonephric kidneys for excretion
  • Brain with about 10 pairs of cranial nerves; lateral line is a sensory organ
  • Separate sexes; some hagfish species may be hermaphroditic
  • Development may be direct or indirect
  • Secrete large amounts of slime for protection from predators

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Description

Explore the intriguing superclass Agnatha, which includes unique jawless fish such as lampreys and hagfish. Learn about their evolutionary history, classification, and ecological roles. This quiz will test your understanding of their characteristics and habitats.

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