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2/29/2012 Simple Invertebrates Chapter 15, Section 1 6 Kingdom Review • • • • • • Archaebacteria Eubacteria Protist Fungi Plant Animal 1 2/29/2012 Animal Characteristics • To compare animals, look at: – Type of body plan – Presence or absence of a head (Nervous system) • Nervous System - an organ system containing specialized cells that coordinate the actions of an animal and transmit signals between different parts of its body – The way food is digested and/or absorbed (Digestive System) • Digestive system – the organs/structures used to break down food • Invertebrates – an animal without a backbone – Make up ~97% of all animal species • Examples: – Clams – Grasshoppers – Earth worms 2 2/29/2012 Invertebrate Characteristics • Body Plan: – Invertebrates have 3 basic body plans • Asymmetrical • Bilateral symmetry • Radial symmetry Invertebrate Characteristics – Symmetry - the identical reflection of two sides • In order to be symmetrical, the right side of the pattern or object is exactly the same as the left side of the pattern or object. 3 2/29/2012 Body Plans • Asymmetrical – without symmetry – Example: sponges Body Plans • Bilateral symmetry – a body plan in which 2 halves of an organism’s body are mirror images of each other – Most animals have this – 2 similar halves – Examples: butterflies, crabs, dogs 4 2/29/2012 Body Plans • Radial symmetry – a body plan in which the parts of the body are arranged in a circle around a central point – Example: sea anemone, star fish, daisy Invertebrate Nervous Systems • Some have no brain or head – No nervous system • Some have fibers, called nerves – Nerves – carry signals to control movements of an organisms body 5 2/29/2012 Invertebrate Nervous Systems • Simple invertebrates have nerves arranged in networks or nerve cords throughout their body Invertebrate Nervous Systems • Some invertebrates have ganglia – Ganglia – groups of nerve cells • Ganglia occur throughout the body and control different body parts 6 2/29/2012 Invertebrate Nervous Systems • More complex invertebrates have a brain and head – The brain controls the many different nerves in different parts of the body Invertebrate Digestive System • Almost all animals (including invertebrates) digest food in a central gut – Gut – the pouch where food is digested in animals – The gut is lined with cells that release powerful enzymes • Enzymes break food down into small particles that cells can absorb 7 2/29/2012 Invertebrate Digestive System • Some animals have a coelom – Coelom – a cavity in the body of some animals where the gut and organs are located – It allows the gut to move food without interference from the movements of the body – Other organs (heart, lungs, etc.) may be in the coelom • Are separated from the gut Groups of Invertebrates 8 2/29/2012 Sponges • Originally thought to be plants • Placed in the animal kingdom because: – Can not make their own food – Must eat other organisms Sponge Characteristics • • • • • • The simplest animals Invertebrates Body plan = asymmetrical No brain/head No nerves No gut 9 2/29/2012 Sponge Characteristics • Can move, but are very slow • Live in water – Most found in salt water • Have a skeleton – made of spicules or spongin • Spicule – needle-like splinters • Spongin – a protein – Supports the body of the sponge – Protects the sponge from predetors Kinds of Sponges – Classified by the types of skelton that they have – Bath sponges • Skeleton is made of spongin • Are soft 10 2/29/2012 Kinds of Sponges – Silica sponges • Made of silicate (the material we use to make glass) • Largest class • Skeleton made of spicules Kinds of Sponges – Calcium-carbonate sponges • Spicules made of calcium-carbonate • Calcium carbon is the material that makes the shells of shellfish 11 2/29/2012 How Sponges Eat • Sponges have tiny holes on the outside of their body – pores • Water is pumped into the sponge body through pores How Sponges Eat • Special cells, collar cells, filter food particles and microorganisms from the water • The rest of the water flows into a central cavity and out a hole in the top of the sponge – the osculum 12 2/29/2012 • • • • Cnidarians In phylum cnidaria – Greek word for “nettle” More complex than sponges All Cnidarians have stinging cells 3 classes – Hydras – Jellyfish – Sea Anemones and corals Cnidarian Body Plan • Come in 2 forms: – Medusa – looks like a mushroom • Example: Jelly Fish – Polyp – shaped like vases and usually attached to a surface • Example: Sea Anemone 13 2/29/2012 Cnidarian Body Plan • Most Cnidarians spend their life as a polyp – Some are polyps and medusas at different times in their life • What type of body plan are these forms? How Cnidarians Eat • All cnidarians have long tentacles covered with special stinging cells – another organism brushes against the cnidarian – 100’s of stinging cells fire into the organism and release a paralyzing toxin • Each stinging cells uses water pressure to fire a nematocyst (a tiny barbed spear) – Cnidarian is able to ingest their prey while it is paralyzed 14 2/29/2012 Cnidarian Nervous System • No Brain • Have a nerve net – A simple network of cells – Controls the movements of the body and the tentacles • Medusas have a nerve ring in the center of its nerve net – Coordinates the swimming Flat Worms • Body Plan Bilateral symmetry • Are flat 15 2/29/2012 • 3 classes: Flat Worms – Planarians • • • • Have 2, large, unblinking eyespots Small Live on water and land Digestive System – – Eat other animals/parts of animals – Digest food in a gut • Nervous System – – Clearly defined head with ganglia making up a primitive brain » Nerves connect parallel nerve cords – Have sensory lobes » Bumps on each side of the head used for detecting food Flat Worms – Flukes and Tapeworms • Parasites • Most live and reproduce inside the bodies of other animals • Nervous System – – Tiny heads without eyespots or sensory lobes • Digestive System – – Have special suckers and hooks for attaching to the host – No gut » Absorb nutrients from the intestines of their host 16 2/29/2012 • • • • • • Round Worms Aka - nematodes Are round when viewed in cross section Tiny, but long and slender Bilateral symmetry Most are parasites Digestive System – break down dead tissues of plants and animals • Nervous System – simple – A ring of ganglia forms a primitive brain – Parallel nerve cords run the length of their body Mollusks and Annelid Worms Chapter 15, Section 2 17 2/29/2012 Circulatory System • Circulatory system - an organ system that passes nutrients, gases, hormones, blood cells, etc. to and from cells in the body – Open circulatory system – a simple heart pumps blood thru spaces called sinuses – Closed circulatory system – a heart circulates blood thru a network of vessels that forms a closed loop Annelid Worms • Aka – Segmented Worms – Have segments – Segments – identical, or almost identical repeating body parts • 3 classes: – Earthworms – Bristle worms – Leeches 18 2/29/2012 Annelid Worms • More complex than flatworms and roundworms • Closed Circulatory System • Digestive System - Have coelom • Nervous system– ganglia in each segment – Brain in a head – A nerve cord connects the brain and the ganglia Mollusks • 2nd largest phylum of animals • Most live in the ocean – Some can live in freshwater or on land 19 2/29/2012 • 3 classes: Mollusks – Gastropods (slugs and snails) • Digestive system: – have a ribbon-like tongue covered with teeth » Teeth called radula » Used to scrape algae off of rocks, chunks of tissue from seaweed, or pieces of leaves off of plants • Open Circulatory System • Nervous System – complex ganglia Mollusks – Bivalves (clams and other two-shelled shellfish) • Digestive system – sit in 1 place and filter tiny plants, bacteria and other particles from the water around them • Open Circulatory System • Nervous System – complex ganglia 20 2/29/2012 Mollusks – Cephalopods (squids and octopuses) • Digestive system – use tentacles to grab their prey and place it in powerful jaws • Closed Circulatory System • Nervous System – more complex than other mollusks – Have a brain that connects all of the ganglia – Smartest of the invertebrates Mollusks • Share the same body parts – Foot: • broad and muscular • Is used to move – Visceral mass: • Contains gills, guts, and other organs • Located in the coelom – Mantle: • Layer of tissue that covers the visceral mass • Protects mollusks that do not have a shell See Figure 15 on page 353 – Shell: • Secreted by the outside of the mantle • Protects the mollusk • Keeps it from drying out 21