Questions and Answers
What is the meaning of ectothermic?
What are the characteristics of fish?
Backbone, gills, aquatic lifestyle, mostly ectothermic, lack vocal cords.
Which of these organisms are NOT considered fish?
What are jawless fish known for?
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Jawed fish were the first organisms to evolve jaws.
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When did spiny sharks evolve?
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Lobe-fin fish have fins that are ______ and extend from the body on a single stalk.
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What is unique to ray-fin fish?
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What type of skeleton do cartilaginous fish have?
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How long ago did sharks evolve?
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What differentiates rays from skates?
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What are the closest living relatives of chimaeras?
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What makes cartilaginous fish unique?
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How do bony fish's skeletons differ from those of cartilaginous fish?
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What characteristic do actinopterygii fish exhibit?
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What defines sarcopterygii fish?
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Study Notes
Ectothermic
- Organisms like fish are classified as ectothermic, meaning they rely on external sources to regulate their body temperature.
Characteristics of Fish
- All fish possess a backbone, unique to vertebrates, providing nerve protection.
- Gills enable fish to breathe by absorbing oxygen from water.
- Fish are primarily aquatic, living in water, and must return if they briefly come on land.
- Predominantly ectothermic, most fish cannot generate their own body heat.
- Fish lack vocal cords but produce sounds through other methods.
Organisms that ARE NOT Fish
- Whales: Mammals, breathe air, lack gills.
- Jellyfish: Cnidarians, no backbone or gills.
- Sea Snakes: Reptiles, able to come on land, lack gills.
- Lobsters: Crustaceans, possess an endoskeleton, and have legs.
Jawless Fish
- First fish and vertebrates evolved roughly 530 million years ago.
- They lack jaws, feeding by filtering water.
- Example: Lamprey.
Jawed Fish
- Emerged approximately 430 million years ago, following jawless fish.
- Included placoderms, early armored jawed fishes.
- Fossils like Bothriolepis candensis reveal their hard, dense scales.
Spiny Sharks
- Resembled modern sharks but had tiny scales covering their skin.
- Evolved about 420 million years ago and became extinct nearly 250 million years ago.
Lobe-fin Fish
- Characterized by fleshy fins on a single stalk extending from the body.
- Evolved around 419 million years ago; lungfish are a living example.
Ray-fin Fish
- Fins are webs of skin over bony spines, making up 99% of current fish species.
- Evolved just over 359 million years ago; examples include ocean sunfish.
Cartilaginous Fish
- Skeletons made of cartilage instead of bone.
- Lack a gene that allows cartilage to convert to bone, using cartilage for protection instead.
Cartilage
- A firm yet flexible connective tissue that forms the skeleton of cartilaginous fish, evolved around 395 million years ago.
Sharks
- Aquatic fish with tooth-like scales, cartilaginous skeletons; earliest known sharks appeared over 420 million years ago.
- Modern sharks evolved roughly 35 million years ago; includes the whale shark, the largest fish.
Rays
- Flattened bodies with ventral gills, evolved around 150 million years ago.
- Give birth to live offspring, unlike skates.
Skates
- Similar body shape and evolutionary timeline to rays; lay eggs instead of live birth.
Chimaeras
- Closest living relatives to sharks, branched off nearly 400 million years ago.
- Reside in deep waters, possess smooth skin and a venomous spine.
Unique Features of Cartilaginous Fish
- Skeletons made of cartilage.
- Presence of spiracles for breathing.
- Dermal denticles (skin teeth) for protection.
- Absence of swim bladders.
- Utilize internal fertilization for reproduction.
Unique Features of Bony Fish
- Skeletons composed of bones, providing protection to internal organs.
- Bilaterally flattened bodies with mirror-image sides.
- Most possess swim bladders for buoyancy control.
- Typically have 3-5 pairs of gill slits protected by an operculum.
- Predominately reproduce through external fertilization, releasing gametes into the water.
- Scales are usually smooth and overlapping.
Actinopterygii
- Characteristics include fins with skin stretched over multiple spines and a single dorsal fin.
- Examples include sunfish, salmon, and pufferfish.
Sarcopterygii
- Features fleshy fins attached by a single bone; often have two dorsal fins.
- Examples include coelacanth and lungfish.
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Description
Explore essential terms and definitions related to fish in this informative flashcard set. Learn about the characteristics of fish, including their ectothermic nature and unique anatomical features. Perfect for students studying animal invertebrates and their classifications.
