UNIT 1 - INVERTEBRATES II

ARTHROPODS


Characteristics

• They live everywhere: on land , in the air and in the water.
  
• It is the biggest group of invertebrates.
  
• They all have external skeleton to protect their body.
  
• They all have many jointed legs.
  
• The body is divided into segments.
  
• They can be herbivores, carnivores or omnivores.
  

Arthropods classification

• Insects: It is the biggest group of arthropods. Their body is divided into 3 parts (head, thorax and abdomen). They have two antennae. They can have wings.
  
• Arachnids: Their body is divided into two parts cephalothorax (head and thorax together)and abdomen. they don have antennae or wings.
  
• Crustaceans: The majority of crustaceans have a body divided into two parts: cephalothorax and abdomen. They have two antennae and don't have wings. 
• Myriapods: they have more than 10 legs
  

SPONGES

Characteristics:

• They live at the bottom of the sea
• They are fixed to the ground. They can't move around.
• Their body is full of holes called pores (pores are used to get water and food).

JELLYFISH

Characteristics:

• They live in the sea. They can be very dangerous.
• They have poisonous tentacles that they use to hunt other animals or to defend themselves.
  
  

ECHINODERMS

Characteristics:

• They are starfish and urchins belong to this group of invertebrates.
• They have many small feet that they use to move along the bottom of the ocean.
  
  

MOLLUSCS

Characteristics:

• They can live in water or in land
• They have a soft body and the majority have a shell.
• There are 3 types of molluscs: with one shell (snails), with two shells (mussels) or with internal shell (squid).
  
  

WORMS

Characteristics:

• They can live in water or in land.
• They have a long soft segmented body made up of rings.