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CHAPTER 14

CHAPTER 14. Mollusks, Annelids, Arthropods, and Echinoderms. Mrs. Nell’s 7 th Grade Life Science Class. MOLLUSKS. Kingdom - Animalia Phylum - Mollusca. Mollusks.

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CHAPTER 14

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  1. CHAPTER 14 Mollusks, Annelids, Arthropods, and Echinoderms Mrs. Nell’s 7th Grade Life Science Class

  2. MOLLUSKS Kingdom- Animalia Phylum- Mollusca

  3. Mollusks Mollusks are the soft-bodied invertebrates in the phylum Mollusca. Mollusks usually have shells (not the slug, though) and bilateral symmetry.

  4. The Body of a Mollusk Mollusks have a soft body covered by a mantle (a thin layer of tissue that makes the shell or protects the body if the mollusk doesn’t have a shell).

  5. Mollusk Gills Mollusks have gills to exchange oxygen and CO2 with the water. gills

  6. Visceral Mass The body organs are located together in what is called the visceral mass.

  7. Mollusk Foot Mollusks have a muscular foot for movement.

  8. Circulatory System Mollusks have an open circulatory system (blood isn’t contained in vessels- blood bathes the mollusk’s organs).

  9. Classifying Mollusks There are three main classes of mollusks: • Gastropods • Bivalves • Cephalopods

  10. Gastropods Gastropods or univalves are the largest class of mollusks. Except for slugs, each has a single shell. Members of the gastropod class are: • Snails • Slugs • Abalones • Whelks • Sea slugs • Conches

  11. Nutrition Gastropods feed on plant material using their radula (a tongue like organ with rows of teeth that works like a file).

  12. Bivalves Bivalves are mollusks with a two-part shell joined by a hinge. Bivalves use siphons to filter feed. Some bivalves are: • Clams • Oysters • Scallops

  13. Bivalve Defense To protect themselves, clams will borrow deep into the sand with their muscular foot. Mussels and oysters will cement themselves to a surface. Scallops will open and close their shell rapidly to move away quickly.

  14. Cephalopods Cephalopods have a large, well-developed head. They have tentacles with strong suckers for capturing prey. They have a well developed nervous system and large eyes. Cephalopods have closed circulatory systems, unlike other mollusks. Some cephalopods are: • Squid • Octopus • Chambered nautilus

  15. Jet Propulsion Cephalopods move by pushing water out through an opening in their head. This jet of water sends it backward. A squid can move more than 60m/s this way.

  16. Squid Internal Anatomy

  17. Importance of Mollusks (I) Mollusks provide food for fish, sea stars, birds, and other organisms.

  18. Importance of Mollusks (II) Some invertebrates, like the hermit crab, use empty mollusk shells as shelter.

  19. Importance of Mollusks (III) Clams, oysters, snails, and scallops are used for food.

  20. Importance of Mollusks (IV) Pearls are produced by many species of mollusks.

  21. ANNELIDS • Kingdom- Animalia • Phylum- Annelida

  22. Segmented Worms Segmented worms belong to the Phylum Annelida. Annelid means “little rings” and describes the segments that makeup the body of these worms. Some members of the annelid phylum are… • Earthworm • Leeches • Marine Worms

  23. Segmented Worms & Mollusks Like mollusks, all segmented worms have a body cavity that holds their organs.

  24. Setae On the outside of each segment, annelids have little bristle-like structures called setae that help them move. Segmented worms also use the setae to help them stay in the soil if a bird gets a hold of them!

  25. Earthworms Earthworms eat soil. They use their crop for storage and their gizzard to grind the soil. Digested food moves to the intestine where it is broken down and absorbed by the blood. Undigested soil and waste leave the worm through the anus.

  26. Leeches Leeches feed on the blood of animals- including humans. They have two suckers that they use to attach to the animal. It will then cut into the flesh and suck out blood. Leeches produce an anesthetic so that the animal doesn’t feel the bite. For centuries leeches were used for blood letting because of the mistaken belief that bodily disorders and fevers were caused by an excess of blood. Today leeches are used to keep blood flowing to reattach body parts.

  27. Marine Worms Marine worms also have segments with setae. Some marine worms trap food in tentacles. Others build tubes to hide in.

  28. Annelids & Mollusks- related? Scientists think segmented worms and mollusks share a common ancestor. They were the first of the animal groups to have bodies with space for the body organs, and they both have a larva stage early in their development.

  29. ARTHROPODS • Kingdom- Animalia • Phylum- Arthropoda

  30. ARTHROPODS Arthropods make up the largest phylum of animals in the animal kingdom. Members of the arthropod phylum include… • Insects • Arachnids • Centipedes • Millipedes • Crustaceans

  31. Molting Caterpillar

  32. The Body of an Arthropod Arthropoda means “jointed foot” and describes the jointed appendages of arthropods. The appendages on an arthropod include legs antennae, claws, and pinchers.

  33. Arthropods and segmented worms- related? The bodies of arthropods are divided into segments like those of segmented worms so scientists hypothesize they may have a common ancestor.

  34. Exoskeletons All arthropods have an external covering called the exoskeleton that protects the body. It is made of protein and a carbohydrate called chitin. Once the arthropod outgrows its shell it will molt.

  35. Insect • Kingdom- Animalia • Phylum- Arthropoda • Class- Insecta

  36. Insects Insects have three body regions: a head, thorax, and an abdomen. The head has a pair of antennae, eyes, and a mouth. The thorax has three pairs of jointed legs and sometimes wings. The abdomen doesn’t have wings or legs attached.

  37. The Body of an Insect Insects have open circulatory systems. For their respiratory system they have openings called spiracles on the abdomen and thorax through which air enters and waste gases are expelled.

  38. Metamorphosis Many species of insects go through a series of changes called metamorphosis. Most insects (butterflies, beetles, ants, bees, moths, flies…) develop through complete metamorphosis. There are four stages of development: • Egg • Larva • Pupa • Adult

  39. Incomplete Metamorphosis Grasshoppers, silverfish, lice, and crickets develop through incomplete metamorphosis. The three stages of development are egg, nymph (a small adult without wings), and adult.

  40. Arachnid • Kingdom- Animalia • Phylum- Arthropoda • Class- Arachnida

  41. Arachnids Arachnids are arthropods with only two body regions (the cephalothorax and abdomen). They have four pairs of legs but no antennae. Arachnids have 8 legs and poison glands, stingers, or fangs. Some arachnids are: • Spiders • Scorpions • Mites • Ticks

  42. Centipede/Millipede • Kingdom- Animalia • Phylum- Arthropoda • Class- Chilopoda/Diplopoda

  43. Centipedes & Millipedes Centipedes have one pair of jointed legs per segment. Millipedes have two per segment. Centipedes have a pair of poison claws to inject venom into their prey (they eat snails, slugs, and worms). Millipedes feed on plants.

  44. Crustacean • Kingdom- Animalia • Phylum- Arthropoda • Class- Crustacea

  45. Crustaceans Crustaceans are arthropods that have one or two antennae and jaws called mandibles for crushing food. They have five pairs of legs. The claws are for catching and holding food. The other four pairs are walking legs. Some members of the class Crustacea are: • Crabs • Crayfish • Lobsters • Shrimp • Barnacles • Pill bugs • Water fleas

  46. Blue Crabs A male crab, or "Jimmy", has a long narrow, inverted "T" shaped abdomen and has blue tipped claws. A female crab can be easily identified by the shape of her abdomen. Abdomen of mature female crab Abdomen of immature female crab

  47. “Jimmy” Some watermen say that a male blue crab looks like it has the Washington Monument on his belly!

  48. “Sally” An immature female, called "she-crab" or "Sally," has an inverted "V" (or triangular) shaped abdomen.

  49. “Sook” An adult female, called a "sook," has an inverted "U" (dome) shaped abdomen.Some watermen say that a sook has the U.S. Capitol Building on her belly! Another easy way to tell a male from a female is that all female crabs "paint their fingernails" (have red tipped claws)- males do not.

  50. Pesticides and Insects Most insects are harmless, but farmers who are concerned about crop yields often use pesticides (chemicals that kill undesirable plants and insects).

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