Presentation on theme: "Chapter 2, Lesson 1 What are invertebrates?"— Presentation transcript:
1Chapter 2, Lesson 1 What are invertebrates? Animals have many things in common. They also have many things that are different. These features can be used to classify animals.
2SymmetryAnimals have different body shapes. Most animals have symmetry. Symmetry means that parts of an animal’s body match up. The body parts match up around a midpoint or line. Some animals have no symmetry. We can use symmetry to classify animals.Sea urchins have symmetry.Sponge does NOT have symmetry.
3Backbone or No Backbone Some animals have a backbone and others do not. A vertebrate is an animal that has a backbone. An animal without a backbone is an invertebrate.Most animals are invertebrates. Some invertebrates have a hard outer covering. Others have a skeleton inside their bodies.
4Invertebrate Groups Mollusks Cnidarians Sponges Echinoderms Flatworms RoundwormsSegmented wormsArthropods
5Sponge facts Simplest kind of invertebrate Most are shaped like a sack with an opening at the topLive under waterExample: sponge
6Cnidarians Have arm-like parts called tentacles Stinging cells at the end of each tentacleStun preySome stay in one placeOthers float or swimExamples: corals, jellyfish
7Mollusks Have a shell Some have shells inside the body Most live in waterSome swimOthers stay in one placeSnails and slugs are the only mollusks that live on landExamples: clams, oysters, octopuses, squid, and snails
8Echinoderms Spiny skin Have a support structure inside the body called an endoskeleton (means inside the body)Example: sea urchin
9Quick Check What are two ways we can classify animals? All mollusks live in water. _________A sponge is the simplest kind of invertebrate. __________An echinoderm has soft skin. _________Cnidarians have tentacles. ___________
10What are arthropods?The largest group of invertebrates is the arthropod group.Arthropods have legs that bend. Their bodies have sections.Some breathe with gills and others through tubes.Every arthropod has an exoskeleton. This is a hard covering on the outside of the body.
11Exoskeleton Keeps the animal safe Keeps the animal from drying out. Quick CheckAn arthropod has a(n) ________ covering.The covering is on the ________ of the body.Examples: lady beetle, praying mantis, moth
12More examples of arthropods Insects- have one pair of antennae, three pairs of legs, one or two pairs of wings, and three body sections.Arachnids- include spiders, ticks, and scorpions. They have four pairs of legs, two body sections, and fangs.
13Examples ContinuedCrustaceans- such as crabs and shrimps, have two pairs of antennae and two to three body sections. They can chewCentipedes and millipedes- Centipedes have one pair of legs on each body section. Millipedes have two pairs of legs on each body section.
14How are worms classified? There are 3 kinds of worms: flatworms, roundworms, and segmented worms.
15Flatworms Simplest worms Flat bodies They have a head and a tail Most do not hurt other living thingsSome live inside other animals.
16Roundworms They have thin bodies with pointed ends. Not as thin as flatwormsFood comes into openingWaste leaves through another opening.Most live inside other animals.
17Segmented Worms Bodies are divided into parts, or segments. The parts are the same, except for the head and tail ends.Each has an opening for the digestive system.Most live on landThey do NOT live inside other animals.Earthworms, sandworms, and leeches are segmented worms.
18Quick Check Write the letter for the fact about each worm. ______flatworms______ segmented worms______ roundwormsA. thin bodies with pointed endsB. do not live in other animalsC. simplest kind of worms