First 482 words of the document:
Animal Phyla The chitin exoskeleton protects the vital organs, All vertebrates have a vertebral column and
reduces water loss, supports the insect, point of have a developed brain, which is protected by the
There are four main groups;- attachment for the muscles and protects the cranium
- Annelids - worms organism from predators.
- Arthropods - insects The disadvantages of having an exoskeleton are
- Insects that it's fixed in size, so that animal has to shed
its exoskeleton, called ecdysis, and grow a new
- Vertebrates fish, birds, reptiles, one which takes time to harden.
mammals and amphibians This leaves the animal vulnerable to predators.
NOTE- INSECTS AND ATHROPODS ARE THE
This is the most successful group of animals,
Annelids: conquering land, air and water.
Members include worms, tapeworms and While insects are classed into the arthropods
earthworms. phylum but are sub-classed as insects due to;-
The features include;- - three pairs of jointed legs
- a thin, segmented body - head antennae and compound eyes
- segments are specialised for a particular - gas exchange via gills or tracheae
function - wings
- hydrostatic skeleton for water support - 2 pairs of wings and 3 pairs of legs are
- closed circulation system with respiratory characteristics of insects. However, fleas
pigments and lice have evolved to lose these
- thin, permeable skin for gas exchange features.
- partitioned body (septa)
- haemocoel which is a fluid filled body Vertebrates:
cavity There are five vertebrate groups;-
- Primitive brain in head and nervous - fish
system along the body. - reptiles
Arthropods: - birds
Members include millipedes, centipedes, - mammals
crustaceans, spiders and insects.
The features include;- Fish characteristics gills, scales and fins
- body divided into three segments Reptile characteristics land-living, dry scaly
- head, thorax and abdomen skin, eggs are laid on land but fertilised internally.
- well-developed brain Amphibians soft moist skin, young are aquatic
- chitin exoskeleton with gills, adults are land living with simple lungs.
- open circulation Mammal characteristics skin has hairs, give
- cavity surrounding the body organs birth to live young, feed young with milk. Divided
into another two groups, marsupials (babies born
- Paired, jointed legs. and kept in pouches) and placentals.
There are two evolutionary developments for Marsupials young are very immature at birth
arthropods, which are jointed les and chitin and develop in the mother's pouch.
exoskeleton. Placentals young develop in the womb and
The joined legs are used for walking, swimming, obtain nourishment through the placenta before
feeding, reproducing, jumping and ventilation. birth.