One foot, two feet …

What is an animal with one foot, two feet, three feet …?

An appendage, such as a foot or a leg, is used for locomotion – walking, moving, or running.

Ped or pod means foot (leg) or feet (legs).

A mollusk, such as a snail or a slug, is an example of an animal with one foot. It is a gastropod – it is a body of one piece. Gastropod means stomach foot.

An animal that walks with two feet is a biped. A bird is a biped.

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Common Marine Hermit Crab

The Common Marine Hermit Crab (Pagurus bernhardus) is a saltwater aquatic decapod (10-armed) crustacean. It is also known as the Soldier Crab.

Hermit crabs include the Marine Hermit Crab, which lives in saltwater, and the Land Hermit Crab, which is terrestrial in tropical regions.

The Common Marine Hermit Crab is a crab inside a shell – its mobile home. It finds empty mollusc shells to live in. It has a long soft body – not like land crabs which have a hard exo-skeleton – which is why it looks for a hard shell to protect it. It can put its whole body inside the shell. As it grows, it looks for larger shells.

The Common Marine Hermit Crab has a spirally-curved soft body (abdomen) with a columella on the tip, which is used to hold onto the shell it occupies. It has 10 appendages (legs, called pereiopods), but two of them are claws, called nippers, pinchers, or chelipeds. Its large black compound eyes are at the end of an eyestalk. It has gills to breathe (like fish).

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What is a pedipalp?

What is a pedipalp?

A pedipalp is an appendage (like an antennae) of an arachnid (spiders and scorpions).

An arachnid has two pedipalps which end in sensory organs in spiders and pincers in scorpions.

‘Pedi’ means foot and ‘palp’ means touching.

Feather Duster Worm

The Feather Duster Worm (Sabellastarte spectabilis) is a tropical marine worm, or bristleworm – a polychaete. It is also called the Fan Worm. Some are sedentary (sessile) and some are mobile (errant). It is an annelid. It looks like a plant, but it is an animal.

The sedentary Feather Duster Worm lives in an elongated tube. The tube looks like a rolled-up parchment. It has segments that have appendages, called setae, or bristles, or tentacles, that look like a feather duster. The appendages are brown with white bands.

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