INVERTEBRATES

INVERTEBRATES

1. Characteristics

   • They don't have a backbone
   • Most of them have some protection
     • Hard shell
     • Exoskeleton (a rigid covering)
   • Any have any protection

2. MOLLUSCS

   • Aquatic/some on land
   • Some have a soft body but others have a shell
     • Exoskeleton + mantle (protection)
       • Some of them have a muscular foot
   • Types
     • Gastropods
       • Some: spiral shell (snails)/ no shell
         • Head and body + 4 tentacles
       • herbivores
     • Bivalves
       • They have two shells (valves)
         • A soft body and no head
           • Fiilter-feeders
     • Cephalopods
       • A big head, a mouth and well-developed eyes
         • Long arms and tentacles
           • carnivores

3. ARTHROPODS

   • General features
     • An exoskeleton
     • Jointed parts and legs
   • Insects
     • 6 legs
       • Body: head, thorax and abdomen
         • Many: wings
   • Crustaceans
     • 10 legs
       • Hard exoskeleton
         • Body: same as arachnids
   • Myriapods
     • Many legs
       • Body: head + trunk divided into segmens
   • Arachnids
     • 8 legs
       • Body: cephalothorax + abdomen
   • Useful: eat crustaceans + pollination + get honey
     • Dangerous: diseases + farmers' crops

4. SPONGES (PORIFERA)

   • Aquatic
   • Can't move around
   • A soft body with pores
   • Filter feeders

5. JELLYFISH AND POLYPS

   • Aquatic
   • Carnivores (trap preys with tentacles)
   • JELLYFISH: they float and swim
     • Umbrella-shaped body
       • Mouth+anus underside and tentacles around
   • POLYPS
     • bag-shaped body
       • Suction cup: anchor themselves in the ocean floor

6. ECHINODERMS

   • aquatic
   • Move across the ocean: tiny feet with suction cups
   • Sea urchins
     • A spherical body + spikes
   • Starfish
     • 5 arms from the centre of the body - it grows again

7. ANNELIDS

   • A soft and long body divided into segments
   • In water/on land