Why are whales, dolphins, and seals classified as mammals, not fish?

They are warm-blooded, breathe air with lungs, give birth to live young, and nurse their offspring with milk They have fins and live in water, making them a special type of fish They are classified as mammals because they are larger than fish They are technically classified as reptiles because they are descended from dinosaurs

How do whales breathe while spending most of their lives underwater?

They surface periodically to breathe through blowholes on top of their heads, and can store large amounts of oxygen in their blood and muscles They absorb dissolved oxygen from the water through their skin They have both gills and lungs, using gills when diving deep They breathe through their mouths and have internal oxygen tanks

What makes the blue whale particularly remarkable?

It is the largest animal ever known to have lived on Earth, reaching up to 30 meters and weighing up to 180 tonnes It is the fastest marine mammal, able to swim at 60 km/h It is the only whale species that uses echolocation It is the deepest-diving whale, reaching 3,000 meters

How do dolphins use echolocation?

They produce high-frequency clicks that travel through water; the echoes returning from objects tell them the size, shape, distance, and density of nearby animals They use their eyes to sense electrical fields from other animals They emit light pulses and detect how objects reflect them They sense vibrations in their whiskers, like cats do on land

Sea turtles are reptiles. What key difference distinguishes them from mammals like sea lions?

Sea turtles are cold-blooded (ectothermic), lay eggs on land, and do not nurse young; sea lions are warm-blooded, give birth to live young, and produce milk Sea turtles breathe underwater while sea lions breathe only at the surface There is no significant difference — both are equally adapted to ocean life Sea turtles are faster swimmers than sea lions because they are lighter

Why do leatherback sea turtles travel across entire oceans?

They follow jellyfish populations — their main prey — which migrate seasonally across ocean basins They migrate to warmer water in winter to regulate their body temperature They travel between oceans to find mates, since all turtles of one sex live together They randomly drift across oceans without any navigation ability

How do sea otters help maintain kelp forest ecosystems?

Sea otters eat sea urchins, controlling their populations and preventing them from overgrazing kelp Sea otters fertilize kelp by depositing nutrients in the water Sea otters protect kelp from fish by chasing them away Sea otters have no significant effect on kelp ecosystems

What adaptation allows seals and sea lions to make long, deep dives?

They have elevated myoglobin in their muscles and can slow their heart rate dramatically (diving reflex) to conserve oxygen They absorb dissolved oxygen from the water through their flippers during dives They fill their lungs with an extremely concentrated oxygen mixture before diving Their blood clots temporarily during dives to preserve oxygen for vital organs

Baleen whales differ from toothed whales in which key way?

Baleen whales filter tiny prey through comb-like baleen plates; toothed whales use teeth to catch individual fish and squid, and use echolocation Baleen whales are smaller than toothed whales Toothed whales are found only in freshwater, baleen whales only in saltwater Baleen whales are more closely related to seals than to toothed whales

Humpback whale songs are notable because:

Only male humpbacks sing, the songs evolve over time, and they may travel across ocean basins as whales learn from each other Humpback songs are distress signals produced by both sexes when threatened All whale species sing identical songs — it is an ancient whale language Humpback whale songs are only produced by calves and stop at adulthood