Butterflies and bees do it. Frogs and even salmon do it. What is it? It’s metamorphosis.
The term describes a series of dramatic physical changes that an organism undergoes as it matures. The term comes from the Greek word for “change of form.”
Lots of young animals look different from their parents. But metamorphosis is distinct from just growing up. Some animals emerge from metamorphosis with brand-new organs, such as wings or lungs. Others switch what types of food they eat — or may wind up not eating at all! These differences may benefit animals by minimizing competition for resources between adults and babies of the same species.
Insects, amphibians and certain fish are among the more well-known animals that metamorphose. But they’re not the only ones. Jellyfish, mollusks and sea stars have all been observed undergoing this real-life shapeshifting. Crabs, lobsters and other crustaceans have, too.
Body remodel
Many animals that metamorphose have babies that look entirely different from their adult forms. Think of a frog. Frogs have powerful back legs and lungs. But many frog species start life underwater as tadpoles. Unlike frogs, tadpoles rely on gills and long tails to maneuver underwater.
Jellyfish, meanwhile, start out as free-swimming young called larvae. These larvae attach to hard surfaces and transform into anemone-like polyps. These polyps spend much of their early lives using their tentacles to catch passing prey. Eventually, the tentacles begin to bud into free-floating jellies. They then detach from their home surface and hit the high seas.
Like jellyfish, sea urchins also start their lives as larvae swimming in the ocean. These larvae use long arms to snag phytoplankton to eat. During metamorphosis, a sea urchin grows adult limbs and organs from a cluster of cells inside its body called a rudiment. The urchins absorb their larval arms and mouths into their bodies. Then they drop to the seafloor as newly formed…
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