Invertebrates characteristics The main characteristics of invertebrates is that they haven´t got a spinal column or an internal skeleton. Some invertebrates ,have got a hard shell to protect themselves. Other invertebrates ,have got a rigid covering called an exoskeleton. Some invertebrates ,have got a soft body without protection.
Main groups of invertebrates. Mollusks Mollusks have got soft body ,but most of them have got a hard shell too.
Jellyfish and Polyps They ´have got a soft body. Some of them have got long tentacles .
Sponges They´have got a soft body whit holes called pores .
Annelids They ´have got a long, soft body that is divided into rings called segments.
Arthropods They´have got an exoskeleton and jointed legs that bend . They include insects ,spiders and crustaceans.
Echinoderms Their bodies are covered whit sharp spikes . Some echinoderms have got arms and tentacles .
More arthropods Arthropods are the most numerous group of invertebrates . Some invertebrates live in water ,other invertebrates live on land . Many arthropods can also fly. They ´have got an exoskeleton. Their bodies are divided into jointed parts. They ´have also jointed legs .
Insects Insects have got six legs . Their bodies have got three main parts : the head , thorax and abdomen . Many insects have got wings .
Arachnids Arachnids have got eight legs . Their bodies are divided into two main parts ; the cephalothorax and the abdomen.
Crustaceans Crustaceans have got ten legs . Their bodies are divided into two main parts : the cephalothorax and the abdomen .
Myriapods Myriapods have got many legs. Their bodies are divided into two main parts : the head and the trunk.
More mollusks They ´have all got soft bodies . Most mollusks have got a hard shell and a thin layer next to their shell called the mantle .
Mollusks Bivalves Bivalves have got a shell whit two parts , called valves . They´have got a soft body and no head. Bivalves are filter feeders . They filter water to extract nutrients.
Mollusks Gastropods Many gastropods, have got a spiral shell . Other gastropods ,haven´t got a shell. Gastropods have got a head and body . They ´have also got four tentacles. Most gastropods are herbibores .
Mollusks Cephalopods Cephalopods have got a head whit a mouth and well- developed eyes . They ´have also got long arms to catch their food. Squid have got tentacles too. Most cephalopods are carnivores.