Kingdom animalia Invertebrates

1. Kingdom animaliaInvertebrates Chapters 24, 25, 26, and 27

2. Invertebrate phyla • Phylum Porifera(ex. Sponge & sea cucumber) • Phylum Cnidaria(ex. jellyfish & hydra) • Phylum Platyhelminthes (ex. Planaria & fluke) • Phylum Nematoda(ex. hookworms & pinworms) • Phylum Mollusca (ex. Octopus, snail, & oyster) • Phylum Annelida (ex. Earthworm & leech) • Phylum Arthropoda(ex. Insects, arachnids, & crustaceans) • Phylum Echinodermata (ex. Sea urchin & sand dollar) • Phylum Chordata(ex. Lancelet & tunicates)

3. Invertebrate Evolution Phylum Porifera Phylum Cnidaria Phylum Platyhelminthes Phylum Nematoda Phylum Mollusca Phylum Annelida Phylum Arthopoda Phylum Echinodermata Phylum Chordata

4. Phylum porifera*Cellular Level of Organization • Organisms in the phylum Porifera are among the simplest animals • Many sponges are radially symmetrical • Their parts are arranged around a central axis • Choanocytes are specialized cells that make up poriferans. Central axis

5. Phylum porifera • Filter feeders: • Flagellated choanocytes filter food from the water passing through the porous body • Sessile: stay in one place Choanocyte incontact withan amoebocyte Pores WATERFLOW Skeletalfiber Centralcavity Choanocyte Flagella Amoebocyte Figure 18.3C

6. Phylum porifera • The sponge lineage arose very early. • They probably evolved from multicellular choanoflagellates, the group that most likely gave rise to the animal kingdom. Single cell Stalk

7. Phylum Cnidaria*Tissue level organization • Cnidarians are the simplest animals with tissues. • These animals exist in two radially symmetricalforms: • Polyp • Medusa

8. Phylum Cnidaria • Cnidocytes on their tentacles sting prey • The tentacles, controlled by nerves, then push the food through the mouth into a gastrovascularcavity. • In the cavity, the food is digested and then distributed. • Only one opening in digestive system.

9. Phylum Platyhelminthes*Organ level of Organization • Flatworms are the simplest bilateral animals. • Flatworms have organs. • Planarians have a simple nervous system consisting of a brain, sense organs, and branching nerves. • As in cnidarians, the mouth of a flatworm is the only opening for its gastrovascularcavity. Digestive tract(gastrovascularcavity) Nerve cords Mouth Eyespots Nervoustissue clusters Bilateral symmetry

10. Flukes and tapeworms are parasitic flatworms with complex life cycles Mature flukes in bloodvessels of intestine Male Humanhost Female 1 Sexual reproductionof flukes in human;fertilized eggs passout in feces 6 Larva penetratesskin andblood vessels 2 Eggs hatchin water 5 Larva thatinfects human 3 Larvathatinfectssnail 4 Asexual reproductionof flukes in snail Snail host

11. Phylum Platyhelminthes • Tapeworms can be eaten by cattle and burrow into the intestines and muscles. • If meat is not properly inspected, humans can be infected by eating rare or undercooked beef. Units withreproductivestructures Head Hooks Sucker

12. Quick evolution checkpoint • Porifera, Cnidaria, and Platyhelminthes lack a body cavity. • Nearly all other animals have a body cavity called a coelom. • This cavity is a fluid-filled space between the digestive tract and the body wall. • The cavity aids in movement, cushions organs, and it may help in circulation.

13. Body covering(from ectoderm) Muscle layer(from mesoderm) Pseudocoelom Digestive tract(from endoderm) Body covering(from ectoderm) Coelom Tissue layerlining coelomand suspendinginternal organs(from mesoderm) Digestive tract(from endoderm)

14. Trichinella juvenile Muscle tissue Phylum nematoda*Pseudocoelom • AKA: Roundworms • Nematodes have a body cavity not completely lined by mesoderm called a psuedocoelom. • Like most animals, they possess a complete digestive tract. • This is a tube with a mouth and an anus. (One-way tract) • Many nematodes are free-living. • Others are parasites.

15. Phylum Mollusca*Coelom • Phylum Mollusca is a large and diverse phylum that includes • gastropods, such as snails and slugs • bivalves, such as clams and scallops • cephalopods, such as squids and octopuses

16. Phylum Mollusca • All mollusks have a muscular foot and a mantle • The mantle may secrete a shell which encloses the visceral mass • Mollusks have a true coelom and a circulatory system • Many mollusks feed with a rasping radula

17. Quick evolution checkpoint:After a Body cavity evolved… • Segmentation is the subdivision of some or most of the body into a series of repeated parts, or segments. Anus Brain Mainheart Coelom Digestivetract Segmentwalls Mouth Accessoryheart Nerve cord Excretory organ Blood vessels

18. Segmentation probably evolved as an adaptation for movement

19. Quick Evolution checkpoint:Protostomal larval development • Protostomal larval development: • Earliest type of larval development according to evolution • Mouth is the first opening to develop. • Cells of the embryo cannot be altered.

20. Phylum Annelida*body segmentation & protostomes • Earthworms and other annelids are segmented worms whose mouths develop first in the larval stage. • The segmented bodies of annelids give them added mobility for swimming and burrowing. • An earthworm eats its way through soil. • Most leeches are free-living carnivores, but some suck blood.

21. Phylum arthropoda*jointed appendages Cephalothorax Abdomen • Arthropods are the most numerous and widespread of all animals. • They are segmented animals with exoskeletons and jointed appendages. Thorax Head Antennae(sensoryreception) Swimmingappendages Walking legs Pincer (defense) Mouthparts (feeding)

22. Phylum arthropoda • In terms of numbers, distribution, and diversity, they are the most successful phylum of animals. • Diversity: • Insects • Crustaceans (marine arthropods) • Arachnids • Millipedes & centipedes • Horseshoe crabs are ancient marine arthropods

23. Phylum arthropoda • Insects are the most diverse group of organisms. • They have a three-part body consisting of head, thorax, and abdomen. • The development of many insects includes metamorphosis. Thorax Abdomen Head Antenna Forewing Eye Hindwing Mouthparts

24. Phylum arthropoda • Metamorphosis: • Larvae: specialized for eating and growing • Adults: specialized for dispersal and reproduction

25. Phylum Echinodermata*deuterostome, endoskeleton, radial symmetry • Echinoderms have spiny skin, an endoskeleton, and a water vascular system for movement. • Phylum Echinodermata includes organisms such as sea stars and sea urchins • These organisms are radially symmetrical as adults

26. Phylum echinodermata • The water vascular system has suction-cup-like tube feet used for respiration and locomotion. Anus Spines Stomach TUBE FEET CANALS

27. Phylum chordata*notochord • Notochord: flexible, tough rod that provides support for the animal and gives muscles a place to attach

28. Phylum chordata*notochord • Organisms in this phylum (LIKE US) are segmented animals with four distinctive features: • Dorsal hollow nerve cord • Stiff notochord • Pharyngeal slits behind the mouth • Muscular post-anal tail We’ll study this phylum separately.