A Life in Hiding
A variety of species go to the extreme: They spend most of their lives in hiding. Over millions of years, they have adapted to surviving in habitats that keep them under cover.
Many kinds of clams, for example, burrow into sandy or muddy beaches. Some species live just under the surface, while others dig deeply. A large clam called the geoduck can bury itself 3 feet (1 meter) below the surface.
By burrowing, a clam protects itself from being washed away by waves, drying out in the sun, and being an easy target for predators. It does not need to leave its hiding place to find food. Instead, the clam opens its paired shells and reaches up through the sand with a body part called a siphon. The siphon takes in water, which the clam filters to extract particles of food.
If the clam senses vibrations rippling through the sand, it quickly pulls in its siphon. Vibrations may mean a predator is investigating its hiding spot. The clam also may burrow more deeply to escape. Some clams can dig quickly: The razor clam can move 9 inches (22 centimeters) in 1 minute.
Other animals find safety in living underground, too. Earthworms spend much of the day burrowing through the soil. If caught by a bird’s probing beak, an earthworm struggles to resist being yanked out of the ground. It grabs onto the walls of its burrow with bristles that line its sides. The worm’s hind end also bulges to help clamp it in place.
A mole digging through the earth can send earthworms scuttling out of the soil. Moles eat earthworms and even store them for later, biting them and then stuffing them into holes in their tunnels. A mole rarely needs to poke its head above ground; there, an owl, fox, or weasel might pounce on it.
Many kinds of clams, for example, burrow into sandy or muddy beaches. Some species live just under the surface, while others dig deeply. A large clam called the geoduck can bury itself 3 feet (1 meter) below the surface.
By burrowing, a clam protects itself from being washed away by waves, drying out in the sun, and being an easy target for predators. It does not need to leave its hiding place to find food. Instead, the clam opens its paired shells and reaches up through the sand with a body part called a siphon. The siphon takes in water, which the clam filters to extract particles of food.
If the clam senses vibrations rippling through the sand, it quickly pulls in its siphon. Vibrations may mean a predator is investigating its hiding spot. The clam also may burrow more deeply to escape. Some clams can dig quickly: The razor clam can move 9 inches (22 centimeters) in 1 minute.
Other animals find safety in living underground, too. Earthworms spend much of the day burrowing through the soil. If caught by a bird’s probing beak, an earthworm struggles to resist being yanked out of the ground. It grabs onto the walls of its burrow with bristles that line its sides. The worm’s hind end also bulges to help clamp it in place.
A mole digging through the earth can send earthworms scuttling out of the soil. Moles eat earthworms and even store them for later, biting them and then stuffing them into holes in their tunnels. A mole rarely needs to poke its head above ground; there, an owl, fox, or weasel might pounce on it.
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