Natural Sciences Grade 7 Term 1: Life and Living Biodiversity (PPT 4)

Diversity of Animals: Invertebrates Topic 2 Biodiversity Diversity of Animals: Invertebrates Natural Sciences – Grade 7

Natural Sciences - Grade 7 Invertebrates Animals with no backbones. There are many animals that belong to this group. We will have a look at 2 phyla arthropods molluscs Natural Sciences - Grade 7 3

Invertebrates: Arthropods All arthropods have jointed legs and an exoskeleton. The exoskeleton contains chitin which makes it strong - it protects the soft tissues on the inside. It provides a framework for muscles to attach to. The body of arthropods are divided into segments. 3 examples of classes of arthropods are insects, arachnids and crustaceans. Natural Sciences - Grade 7 4

Natural Sciences - Grade 7 Arthropods: Insects This group is very diverse – more than a million different species have been identified. Examples: beetles, locusts, mosquitoes, bees and ants. Insects are found in nearly all the different environments on the Earth. Natural Sciences - Grade 7 5

Natural Sciences - Grade 7 Arthropods: Insects Insects have – 3 pairs of legs 1 pair of antennae on the head a body that is divided into 3 sections: head with sense organs: eyes, antennae and a mouth thorax with legs and wings abdomen that contains intestines and reproductive organs. Natural Sciences - Grade 7 6

Natural Sciences - Grade 7 Arthropods: Insects Natural Sciences - Grade 7 7

Arthropods: Arachnids Arachnids consist of over 100 000 different species. Examples: spiders, scorpions, harvestmen, ticks and mites Natural Sciences - Grade 7 8

Arthropods: Arachnids Arachnids have – 4 pairs of legs no antennae on the head a body that is divided into 2 sections: head and thorax (cephalothorax) which is joined into one section; it carries sense organs, a mouth and legs. Natural Sciences - Grade 7 9

Arthropods: Arachnids (spider) http://space-facts.com/earth/ Natural Sciences - Grade 7 10

Arthropods: Crustaceans There are about 67 000 different species of crustaceans. Examples: crabs, lobsters, crayfish, shrimp, krill and barnacles. They look very different from each other, even though they belong to the same group. http://space-facts.com/earth/ Natural Sciences - Grade 7 11

Arthropods: Crustaceans Crustaceans have – 5 or more pairs of legs 2 pairs of antennae on the head a body that is divided into 2 sections, but sometimes also 3 sections http://space-facts.com/earth/ Natural Sciences - Grade 7 12

Arthropods: Crustaceans (crab) Natural Sciences - Grade 7 13

Invertebrates: Molluscs Molluscs have soft bodies, for example snails. They have a head and a foot region. The body is covered by a hard shell. The large majority of molluscs live in the sea. Molluscs range from species that are microscopically small to the giant squid. Natural Sciences - Grade 7 14

Invertebrates: Molluscs (land snail) Natural Sciences - Grade 7 15

Natural Sciences - Grade 7 This is a simplified classification of the animal kingdom. Natural Sciences - Grade 7 16