Invertebrates

invertebrates

Ninety percent of all animals on the planet are invertebrates. Invertebrates are animals which do not have a backbone.
Insects, worms, spiders, jellyfish, starfish and crabs are all invertebrates.

Each species has its own life cycle. Many lay eggs, some hatch as larvae and others as miniature adults.

ARTHROPODS

Invertebrates with a hard outer layer and jointed limbs are all known as arthropods. They include Crustaceans, Insects, and Arachnids. They have a varying number of legs.

Crustaceans

Crustaceans are arthropods. Most of them live in water. They have a hard outer layer (an exoskeleton), 7 or more pairs of legs, for feeding and moving, and two pairs of antennae.
This group includes lobsters, shrimps, prawns, crabs, water lice, water fleas, and barnacles.

Insects

Insects are the largest class of arthropods, and one of the most abundant animals on earth. All insects have six legs, and their body is made up of three parts - head, thorax and abdomen. They have antennae on their heads, for feeling. Most insects, including bees, dragonflies, and water boatmen, have wings.

Insects go through several stages of growth before they become adults. This process is called metamorphosis.

Even though insects are small, they have better senses than most bigger animals. They can see colours and hear sounds that people can't hear. They can also detect smell from many kilometres away.

Arachnids

Arachnids are arthropods. Most of them live on land. The group includes spiders, scorpions, mites, and ticks. They have a segmented body divided into two. Eight walking legs grow from the lower section of the body. They have biting or piercing mouth-parts. Arachnids have no antennae.

MOLLUSCS

Molluscs are soft-bodied invertebrates. Most of them have an outer or inner shell. They have a muscular "foot", and/or tentacles. The Mollusc group includes squid, octopus, mussels, clams, snails and slugs.

WORMS

Worms are animals with long soft bodies. There are many different types including flatworms, earthworms and leeches.

invertebrates