Invertebrates and Vertebrates

1. Pgs 28 – 35 and 60 - 62 Invertebrates and Vertebrates

2. Simple Invertebrates • Invertebrates are animals without backbones. • They make up 97% of all animal species. • The differences among invertebrates can be compared by looking at several characteristics: Body plan, presence of a head, and the way food is digested and absorbed.

3. Body Plans • Invertebrates have two basic body plans: Symmetrical or Asymmetrical. • Symmetry can be bilateral, with two similar halves, or radial with similarities coming from a central point. • The simplest invertebrates, sponges have no symmetry.

5. Getting a Head • All animals except sponges have fibers called nerves that carry signals to control the movements of their body. • Some have nerves arranged in networks or cords throughout their body and they do not have a brain or head. • Some have never cells grouped together called ganglia, that control movements of body parts. • More-complex animals have brains contained in heads. • The brain controls most of the body’s functions

6. Don’t You Have Any Guts? • Almost all animals digest food in a central gut. • A gut is a pouch lined with cells that release powerful enzymes that break food down into tiny particles that can be absorbed. • Complex animals have a special space in the body for the gut called the coelom(see luhm). • This allows the gut to move food without interference from the movements of the body.

7. Sponges • Sponges are the simplest animals. • They have no symmetry, head, nerves, or gut. • They cannot make their own food. • All sponges live in water, most in the ocean. • Made of needle like splinters called spicules that support the body. • Large sponges have spicules made of silicate, the same material glass is made from. • Bath sponges are made of spongin, a soft protein.

9. Re-Form and Replace • If a sponge’s body is broken apart, the separate cells can come back together and re-form the same sponge. • Also, new sponges can form from pieces broken off of another sponge. • A sponge can replace its body parts by a process called regeneration.

10. How Do Sponges Eat? • Sponges contain th0usands of tiny holes called pores on the outside of their bodies. • The sponge will bring in water into its body through the pores into its central cavity. • The central cavity has cells called collar cells that filter food particles and microorganisms from the water. • The water will then leave through a hole in the top of the sponge called an osculum.

12. Cnidarians • Cnidarians are organism that release stinging barbs into the skin. • They have stinging cells. • Cnidarians are more complex than sponges. • They have complex tissues, a gut for digesting food, and a nervous system. • Some can even reform if cells become separated.

13. Forms of Cnidarians • There are two forms for cnidarians: medusa and polyp. • The medusa looks like a mushroom with tentacles streaming below and the polyp is shaped like a vase and is attached to a surface. • Most spend their life as a polyp. • Some can spend part of their life as a polyp and a medusa. • Examples include jellyfish and hydras.

15. Kinds of Cnidarians • There are 3 classes of cnidarians: hydras, jellyfish, and sea anemones. • Hydras are live in fresh water and live in polyp form. • Jellyfish spend most of their life as a medusa. • Sea anemones and corals are polyps their whole life. • Corals live in colonies in warm tropical waters.

17. Catching Lunch • All cnidarians have long tentacles covered with special stinging cells. • The stinging cells fire into organisms and release a paralyzing toxin. • When stinging cells are released so is a tiny spear called a nematocyst.

18. You’ve Got Some Nerve • Cnidarians have a simple network of nerve cells called a nerve net. • It controls the movements of the body and tentacles. • Medusas have nerve rings that coordinate swimming motions of the animal. • They do not have brains though.

19. Flatworms • These are the simplest form of worms. • They have bilateral symmetry and a clearly defined head with clearly defined eye spots. • Their eyes cannot focus, but can tell the direction in which light comes. • There are also a bump on each side of the head called sensory lobes. • Flatworms are divided into 3 classes: planarians, flukes and tapeworms.

20. Planarians • They are small; their length is equal to a fingernail. • They live in water and on land. • They eat other animals and digest food in their gut. • They have a brain and nervous system.

21. Flukes and Tapeworms • Flukes and tapeworms are parasites that feed on other living creatures. • The host usually does not dies. • They live and reproduce inside other organisms. • Fertilized eggs pass out of the host’s body in waste.

22. Flukes and Tapeworm Characteristics • If they end up in drinking water or food they can be eaten by another host. • They have tiny heads without eyespots. • They have suckers and hooks to attach to the host. • They live in the gut and absorb nutrients.

23. Roundworms • They are round, long and slender. • They have bilateral symmetry. • Most species are tiny. • They break down dead tissue of plants and animals and can help build rich soils. • They have a simple nervous system, primitive brain and parallel nerve cords. • Most are parasites like the pinworm and hookworm.

25. Vertebrates • Vertebrates are animals with a backbone. • Chordata is the phylum name for vertebrates. • At some point in their life, all chordates have four special body parts: a notochord, hollow nerve cord, pharyngeal pouches and a tail.

26. Getting a Backbone • Most chordates are vertebrates. • Lancelets and tunicates are chordates, but not vertebrates. • The backbone is the characteristics that separate vertebrates from other chordates. • Vertebrae are the bones that make up the backbone. • Vertebrae surround the nerve cord.

27. Vertebrates • Vertebrates also have a well-developed head, protected by a skull. • The skull and vertebrae are made up of bone or cartilage. • Cartilage is the tough flexible parts of our ears and nose. • All vertebrate skeletons start as cartilage and usually turn to bone. • Bone is so hard it can be fossilized and studied.

28. Warm or Cold Vertebrates • Most animals need to stay warm so chemical reactions can occur within our bodies. • Some control their temperatures more than others. • Birds and mammals warm their body by capturing heat released by chemical reactions in their cells. • Their body temperature stays nearly constant. • Animals that do this are called endotherms or warm-blooded animals.

29. Cold-blooded? • Lizards and other animals that do not control their body temperature through the chemical reactions of their cells are called ectotherms. • Their body temperature fluctuates with the temperature of their environment. • Most fish, amphibians, and reptiles are ectotherms or coldblooded.