Science Ch. 3-fish, Amphibians, And Reptiles

Sharks have multiple rows of teeth in their mouths, and they continuously lose and replace their teeth throughout their lives. When a shark loses a tooth, another one grows back in its place. This allows them to constantly have a full set of teeth for hunting and feeding.

Birds and mammals are endotherms because they have the ability to regulate their body temperature internally. Unlike ectotherms, which rely on external sources of heat to regulate their body temperature, endotherms generate heat internally through metabolic processes. Birds and mammals have a high metabolic rate, which allows them to maintain a constant body temperature regardless of the external environment. This adaptation enables them to be active and thrive in a wide range of habitats and climates.

Lizards breathe with their lungs. Unlike sharks, which have gills to extract oxygen from water, lizards are terrestrial animals that require lungs to breathe in oxygen from the air. Larval salamanders also have lungs, but as they develop into adults, they often switch to using gills. Lampreys, on the other hand, are jawless fish that use gills to breathe. Therefore, the correct answer is lizard.

Lampreys and hag-fishes are the correct answer because they are the only fish that do not have jaws, scales, or paired fins. Sharks have jaws and scales, while sturgeons have scales and paired fins. The ocean sunfish has scales and paired fins as well. Lampreys and hag-fishes are unique in their lack of these characteristics.

Adult frogs return to the water to reproduce. This is because frogs lay their eggs in water, and the tadpoles that hatch from these eggs need water to survive and develop. By returning to the water, adult frogs ensure that their offspring have a suitable environment for growth and development. Additionally, water provides protection for the eggs and tadpoles from predators on land. Therefore, reproduction is the main reason why adult frogs return to the water.

The buoyant force is the upward force exerted by a fluid on an object submerged in it. When an object is submerged in water, the water exerts a force on the object in an upward direction, which is known as the buoyant force. This force is what allows objects to float in water or other fluids.

A swim bladder is a gas-filled organ found in bony fish that helps them control their buoyancy. By adjusting the amount of gas in the swim bladder, a fish can either increase or decrease its buoyancy, allowing it to move up or down in the water column. This is important for the fish to maintain its position in the water and conserve energy while swimming.

Amphibians usually begin their lives in the water because they are ectothermic animals that rely on external sources of heat to regulate their body temperature. The water provides a suitable environment for their eggs to develop and hatch into larvae, such as tadpoles. These larvae then undergo metamorphosis, transitioning into adult amphibians that can live both in water and on land. Starting their lives in the water allows amphibians to take advantage of the aquatic resources and protection it provides during their early stages of development.

Paleontologists are scientists who specialize in the study of dinosaurs and fossils. They examine and analyze the remains of ancient organisms, such as bones, teeth, and imprints, to understand their evolutionary history, behavior, and ecological roles. By studying dinosaurs and fossils, paleontologists contribute to our understanding of Earth's history and the evolution of life on the planet.