¡Descarga Lesson 3: Invertebrates - Characteristics, Classification and Examples y más Apuntes en PDF de Biología solo en Docsity! LESSON 3: INVERTEBRATES Invertebrates all share one characteristic: They don't have a backbone or an internal skeleton.Most invertebrates lay eggs. They can be classified into six groups: ARTHROPODS MOLLUSCS SPONGES CNIDARIANS ECHINODERMS ANNELIDS ARTHROPODS This is the largest invertebrate group. AÍ arthropods have an external skeleton called EXOSKELETON They also have jointed legs that bend. Some arthropods have simple lungs. Others, like crabs and lobsters, absorb oxygen through their gills.They are oviparous. As the arthropod gets bigger, it sheds its exoskeleton and grows a new one. Arthropods are divided into four groups: Insects Arachnids Crustaceans Muyriapods Rp» hb Mollucs are soft-bodied invertebrates found on land and in water. Most of them have a hard shell.They absorb oxygen through gilís and reproduce by laying eggs. Snails have a single shell and a single foot which they use to move. They have tentacles on their heads, and each tentacle has an eye at the end of it. They also use their tentacles to feel. Other molluscs, such as mussels, have shells that can open and close. They have a soft body but no head. Octopuses don't have a shell. To move about, they expel jets of water and move their tentacle, SPONGES When you think of sponges, you probably picture the sponge in your Kitchen. Believe it or not, your Kitchen sponge may actually have come from a sea sponge! The sponges are the simplest invertebrates. Sea sponges can be many different colors, sizes, and shapes. Very few animals eat sponges so they can live for a very long time. They don Some types have been found to live over 200 years! Their body texture looks very much like the texture of your Kitchen sponge. Both your Kitchen sponge and a sea sponge get that texture from their pores. Pores are tiny holes in the sponge's body that let water, gases, and food in and out. Where Do Sea Sponges Live? The sea sponge is a type of animal that lives in the worlds oceans.Sea sponges can only survive in saltwater, so if you put them in freshwater, they will quickly die. They are also very sensitive to air and do not like to be taken out of the water because their pores get filled with air. If too many of their pores are filled with air, they will die. Y CNIDARIANS Most cnidarians live in the sea. They have a soft, jelly-like body with one opening surrounded by venomous tentacles. They are divided into two groups: jellyfish and polyps - Jelligfish are almost transparent and their body is gelatinous. Their mouth and their tentacles are in the low part of their body. Their tentacles have toxic substances which they use for prey their food. The poluyp is related to the anemone, and consists of a stomach with a mouth at one end. Poluyps live attached to rocks.They also have tentacles and mouth.But they differ from jellyfish that their mouth and tentacles are in the upper part of their body. Polyps make coral. ECHINODERMS Echinoderm means echino(spiny) and derm means (skin). They live in all parts of the ocean, but mostly on the sea floor.They have an internal structure called endoskeleton, and they are covered by hard, spiny skin. Many echinoderms catch their food by grabbing it with their tiny tube feet. Starfish and sea urchins are examples of echinoderms. Echinoderms Sea stars Brittle stars Sea urchins Sand dollars Sea cucumbers Crinoids a IN The earthworm is a segmented worm. It isn't a parasite. Amnelids don't have a protective body covering. Some annelids breathe through their skin(worms), but others have gills. Examples of annelids are leeches (sanguijuelas) and worms (gusanos). ACTIVITIES 1.Classify these invertebrates and write a sentence to describe each one. It has Picture Cc) shows A/A ...ooooncononononeninannnnonanono It has 2.Classify Arthropods, mollucs, sponges, cnidarians,echinoderms and annelids in this chart: SPIDER, SEA ANEMONE, EARTHWORM, SEA CUCUMBER, STARFISH, SPONGE, OCTOPUS, ANT, CENTIPEDE, JELLYFISH. ARTHROPODS MOLLUSCS SPONGES CNIDARIANS ECHINODERMS ANNELIDS 3. Label the picture of this ant. 10 1 Name: Parts of an Ant head thorax abdomen antenmae legs ] 4.Complete the sentences with the words in the box. skin backbone exoskeleton muscular soft Jellgfist segiments shell thorax. umbrella 1.Arthropods have three parts: head, and abdomen. They also have jointed legs and a protective 2.Echinoderms are protected by hard. 3. have a body called the . They also have long tentacles. 4. Annelids have a long, soft body divided into . 5. Molluscs have a soft, body. Itis often protected by a hard. . 1
