Questions and Answers
What is Class Agnatha known for?
How many species are there in Class Agnatha?
80
What are hagfish known for?
Small eyes and pinkish, gray bodies
Where do Class Agnatha fish live?
Signup and view all the answers
How do Class Agnatha eat?
Signup and view all the answers
What do hagfish do after burrowing into the bodies of a dead fish?
Signup and view all the answers
How many hearts do hagfish have?
Signup and view all the answers
What type of circulatory system do hagfish have?
Signup and view all the answers
How do hagfish evade capture?
Signup and view all the answers
What are lampreys characterized by?
Signup and view all the answers
What do lampreys do after finding a suitable host?
Signup and view all the answers
Where do all lampreys breed?
Signup and view all the answers
What happens after lamprey eggs hatch?
Signup and view all the answers
What is Class Chondrichthyes known for?
Signup and view all the answers
What type of scales cover animals in Class Chondrichthyes?
Signup and view all the answers
How many species of sharks, skates, and rays exist?
Signup and view all the answers
What kind of diet do animals in Class Chondrichthyes have?
Signup and view all the answers
How do sharks locate prey?
Signup and view all the answers
What do sharks have the largest of for any fish?
Signup and view all the answers
What are rays and skates characterized by?
Signup and view all the answers
How many teeth do animals in Chondrichthyes have and what happens when a tooth breaks?
Signup and view all the answers
How many teeth may an animal in Chondrichthyes have in their lifetime?
Signup and view all the answers
Study Notes
Class Agnatha
- Comprises approximately 80 species, including hagfish and lampreys.
- Characterized by jawless structure, smooth skin without plates or scales.
- Features an eel-like body and a cartilaginous skeleton with unpaired fins.
- Notochord remains present throughout their lifespan.
Hagfish
- Possess small, subdermal eyes that act as light detectors.
- Lack vertebrae which differentiates them from other fish.
- Body fluids share nearly the same ion concentration as seawater, allowing them to adapt to their environment.
- Exhibit pinkish-gray coloration with 4-6 short tentacles around the mouth.
Habitat and Feeding
- Found as bottom dwellers in cold marine waters, feeding on small invertebrates or decaying fish.
- Lack biting capability; utilize two movable plates and a rough tongue-like structure for feeding by pinching off flesh chunks.
Feeding Behavior of Hagfish
- Burrow into dead fish through gills, skin, or anus to consume internal organs after entering.
Hagfish Physiology
- Have a total of six hearts.
- Function with an open circulatory system.
- Evade predators by tying bodies into knots or secreting bad-tasting slime, primarily staying hidden in mud burrows.
Lampreys
- Have large eyes and primarily inhabit freshwater, reproducing in these environments.
- Approximately half of all lamprey species are free-living and do not feed as adults; the other half are parasitic, feeding on the blood and fluids of other fish.
Lamprey Feeding Technique
- Attach to hosts using a disk-shaped mouth, scrape a hole with a rough tongue, and secrete an anticoagulant to prevent blood clotting during feeding.
Reproductive Behavior of Lampreys
- Breed exclusively in freshwater, choosing gravel-bottomed shallow streams for spawning.
- Female releases eggs while male fertilizes externally; eggs hatch into larval forms resembling lancelets.
Class Chondrichthyes
- Composed of fish with cartilaginous skeletons, including sharks, skates, and rays, totaling around 800 species.
- Movable jaws and paired fins are characteristic features.
Cartilage
- A flexible, lightweight material consisting of cells embedded within tough fibers of protein, providing structural support in Chondrichthyes.
Feeding and Adaptations in Chondrichthyes
- All species are carnivorous, with some scavenging; diet can include fish, seals, aquatic invertebrates, and plankton.
- Covered in placoid scales, which are tooth-like spines that reduce water turbulence, enhancing swimming efficiency.
Sharks
- Exhibit large, curved tails and torpedo-shaped bodies, swimming with a side-to-side motion from an asymmetrical tail fin.
- Pectoral fins are located behind the head, resembling wing structures of an airplane.
Teeth and Sensory Systems
- Have 6-20 rows of inward-pointing teeth that are self-replacing; can possess up to 2,000 teeth in their lifetime.
- Utilize heightened senses to locate prey: keen sense of smell, developed lateral line system, excellent vision in low light, and sensitivity to electrical fields from other animals.
Brain Size
- Sharks possess the largest brain relative to body size of any fish.
Rays and Skates
- Flat bodies with paired wing-like pectoral fins; some have whip-like tails.
- Rays typically have diamond or disc-shaped bodies, while skates have triangular shapes; sizes generally do not exceed 3.3 feet in length.
- Primarily bottom dwellers, with their flat shape aiding in camouflage and movement along the ocean floor.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Explore the unique characteristics and behaviors of Agnatha, including hagfish and lampreys. This quiz covers their anatomy, habitats, and feeding methods, revealing the adaptations that make these jawless fish distinct in the marine environment.
