Hint: Even without a locomotory organ, animals can move by many methods for various reasons.
- One of the main features of an animal is that it can move. It can be by walk, run, jump, hop, swim, slither, fly etc. and is done in search of food, a mate, a microhabitat etc. Other than this, some animals depend on their environment to transport them, like, sailing (some jellyfishes), rolling (some beetles and spiders) and riding other animals.
- This type of movement is called passive locomotion. The locomotory organs, structures for movement, include legs, arms, wings, fins, cilia, tails etc.
There are four types of environment for movement: aquatic, terrestrial (including arboreal), fossorial and aerial.
- Animals travelling in aquatic environments adapt various types of movement and swimming is one of them. Fishes generate the thrust by moving their body from side-to-side, resulting in a wave motion. Marine mammals oscillate their body in an up-and-down direction, penguins and diving ducks move underwater in a way that is called ‘aquatic flying’. Some fishes do not use the wave motion, instead they propel themselves to move, e.g. seahorses.
In the benthic zone, many animals walk on the sea bed, for example, echinoderms use their tube feet to move, sea urchins use their spines for movement, crabs walk sideways etc.
- Terrestrial form of locomotion includes walking, running, jumping etc. Animals like kangaroo, hare, and hopping mouse etc. jump to catch a prey or run from a predator. Peristalsis movement is adopted by earthworms to move. Many arboreal animals like gibbons, move by swinging from branch to branch with their hands. Other terrestrial movements include walking, looping, running, sliding etc.
- Burrowing animals show fossorial movement like golden mole, marsupial mole etc. they move rapidly through the loose substrate.
- Aerial movement includes active flight. Animals which can fly have wings, low body weight, fusiform shape, powerful flight muscles etc. Some animals glide in the air rather than taking active flights. This method involves flying at a greater distance horizontally than vertically and therefore has a simple descent like a parachute. E.g. gliding ants, flying frog etc. Some birds soar without wing flapping like vulture.
Note: Other than self-propelled movements, many animals move by passive locomotion like moving with the wind, water currents, and tides, moving with an animal transport, parasites moving on host etc.