Whales make sounds to communicate, find one another, navigate and locate food. Sound travels far more effectively through seawater than light, so acoustic signals remain useful in dark depths or across distances where vision fails. Different species produce clicks, whistles, pulses, moans and patterned songs. NOAA’s overview of why whales make sounds separates two broad…
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Dolphins are mammals, not fish. Their ancestors lived on land and modern dolphins still carry the defining mammal traits beneath a body streamlined for open water. They breathe air with lungs, nurse calves with milk and regulate an internal body temperature that stays warmer than the surrounding sea. NOAA’s direct answer to whether dolphins are…
Most fish have body temperatures that stay close to the surrounding water, but a small group retains metabolic heat. Tuna and some sharks warm selected tissues. The opah goes farther by circulating warmed blood through its body, including the heart, giving it the clearest known example of whole-body endothermy in a fish. NOAA’s answer to…
The Australian box jellyfish, Chironex fleckeri, is widely considered the most venomous marine animal. Its nearly transparent bell can trail clusters of tentacles armed with millions of microscopic stinging capsules. Contact can deliver venom rapidly enough to cause extreme pain, cardiovascular collapse and death in severe cases. NOAA’s account of the most venomous marine animal…
