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Invertebrates

Invertebrates . Ms. Youngblood. Body plans. All invertebrates lack a back bone Invertebrates are either asymmetrical or symmetrical. Bilateral vs. Radial Symmetry vs. Asymmetrical. Heads. All animals except sponges have fibers called nerves.

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Invertebrates

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  1. Invertebrates Ms. Youngblood

  2. Body plans • All invertebrates lack a back bone • Invertebrates are either asymmetrical or symmetrical. • Bilateral vs. Radial Symmetry vs. Asymmetrical

  3. Heads • All animals except sponges have fibers called nerves. • Simple invertebrates have nerves arranged in networks or nerve cords throughout their body – they have no brain or head.

  4. In some vertebrates, dozens of nerve cells come together in groups called ganglia. • More complex animals have a brain and a head where the brain is stored.

  5. How about guts? • Almost all animals digest food in a central gut. • The gut is a pouch lined with cells that release powerful enzymes to help break down food. • Complex animals have a special space in the body for the gut. This is the coelom which allows the gut to move food without interference from body movements.

  6. Sponges • Simplest animals • No symmetry, head, nerves, or gut. • Movement is slow and difficult to see.

  7. Sponges Cont’d • All sponges live in water, and most are found in the ocean. • Variety of color and shapes • Skeleton made of needlelike spindles called spicules. • Spicules help classify different types of sponges

  8. Sponges Cont’d • Re-form and Replace • A sponge can re-form, new sponges can grow from broken off pieces, and sponges can regenerate. • Phylum: Porifera • Refers to the tiny holes or pores on the outside of sponges • Filter Food • Osculum • Collar cells

  9. Cnidarians • Cnidaria comes from the Greek word for nettle. • All Cnidarians have stinging cells

  10. Cnidarians • Cnidarians come in two forms, the medusa and the polyp. • A medusa looks like a mushroom with tentacles streaming down. (THINK JELLYFISH) • A polyp is shaped like a vase usually and most often live attached to a surface (THINK SEA ANEMONE)

  11. Cnidarians • Cnidarians have long tentacles covered with special stinging cells. • When a nearby fish brushes against the tentacles, stinging cells fire into the organism and release a paralyzing toxin • Cnidarians have a simple network of nerves called a nerve net. • Medusa’s have a nerve ring in the center of their nerve net.

  12. Flatworms • Simplest group of worms • Bilateral symmetry • Head with unseeing eyes and two sensory lobes • 3 classes : Planarians, Flukes, and Tapeworms • Planarians are largest and predators • Flukes and Tapeworms are parasites

  13. Roundworms • Bilateral symmetry • Most are tiny • A rotton apple lying on the ground can contain up to 100,000 round worms • Simple nervous system • Parasitic

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