2. AP Biology Lecture #49 Non-Vertebrate Animals

3. Characteristics of Animals Animals are: Multicellular Heterotrophs Eukaryotic Have tissues and differentiated cells Eat Reproduce and Develop 1.3 millions species have been identified, estimates of 10 to 200 million exist

4. Early Embryonic Development Sperm and egg meet through fertilization to form a zygote The zygote undergoes mitosis, called cleavage A blastula, or multi- celled hollow ball forms These cells form tissue layers that make up a gastrula

5. Eras of Animal Life Neoproterozoic Era (1 B  542 mya): First fossilized animals are from this time period. Paleozoic Era (542  251 mya): the Cambrian explosion occurs, huge diversity of animal species, including vertebrates, evolve Mesozoic Era (251  65.5 mya): animal life spreads across the planet Cenozoic Era (65.5 mya  present): dinosaurs, birds, and mammals all evolve

6. Body Plans Animals can have radial symmetry, in which the parts of an animal radiate out from the center (starfish) Or they can have bilateral symmetry, with equal left and right sides (lobsters, humans) Animals with a distinct forward facing head at the top of the body have gone through cephalization.

7. Tissue Layers The tissue layers of an animal embryo are called germ layers, and form organs. The ectoderm is the outermost layer and forms the skin and nervous system. The endoderm is the inner layer of the embryo and turns into the digestive system. Some animals have a third layer, called the mesoderm, which forms the other body organs.

8. Body Cavities Some animals have body cavities, a fluid-filled space that separates the digestive tract from the outer body wall, this is called a coelom. Pseudocoelomates have a body cavity that is formed from a different type of tissue. Acoelomates do not have body cavities.

9. Protostomes and Deuterostomes Protostomes, like worms and bugs, develop a mouth first during fetal development. Deuterostomes, like people and starfish, develop an anus before they develop mouths.

10. Invertebrates

11. Invertebrates are animals without a backbone. The main phyla we will talk about are: – Porifera – Cnidaria – Platyhelminthes – Nemotodes – Mollusks – Annelids – Arthropods – Echinodermata – Some chordates

12. Parazoa Invertebrates: animals without backbones Closest lineage to protists Loose federation of cells (unspecialized); no tissues Phylum.: (only one) Porifera (sponges)

13. The Sponges – Phylum Porifera

14. Phylum Porifera are the sponges. They may have radial symmetry, or no symmetry. They are non-motile filter feeders. Individual cells are specialized, but they have no true organs.

15. General Information Size range – 1 cm to 1 cm to 2 meters in diameter Giant Barrel sponges

16. Eumetazoa: Animals with true body tissue The Radiata, I Diploblastic Radial symmetry Phylum: Cnidaria (hydra, jellies, sea anemones, corals) – tissues, but no organs – two cell layers – predators tentacles surround gut opening extracellular digestion – release enzymes into gut cavity – absorption by cells lining gut

17. hydra stinging cell with nematocyst trigger discharged nematocyst undischarged nematocyst tentacles mouth sensory cell stinging cell Stinging cells of Cnidarians

19. The Radiata, II Phylum: Ctenophora (comb jellies) 8 rows of comblike plates of fused cilia (largest animals that use cilia for locomotion) Tentacles with colloblasts (adhesive structures that capture prey)

20. Eumetazoa: The Acoelomates Phy: Platyhelminthes (flatworms, flukes, tapeworms) Bilateral; no body cavity Predators, scavengers, parasites Some cephalization~ development of brain concentration of sense organs in head ectoderm mesoderm endoderm acoelomate

21. Eumetazoa: Pseudocoelomates, I Body cavity partially derived from mesodermally derived tissue Phylum: Rotifera 1st with a complete digestive tract Hydrostatic skeleton Parthenogenesis: type of reproduction in which females produce offspring from unfertilized eggs

22. Eumetazoa: Pseudocoelomates, II Phylum: Nematoda (roundworms) Very widespread group of animals (900,000 sp. ?) Cuticle (tough exoskeleton) Decomposition and nutrient cycling Complete digestive track; no circulatory system many are parasitic hookworm Trichinella spiralis C. elegans

23. The Coelomates: Protostomes, I Phylogenetics debated…. Phy: Nemertea (proboscis and ribbon worms) Complete digestion and closed circulatory system (blood) Phy: the lophophorates (sea mats, tube worms, lamp shells) Lophophore: Circular shaped body fold with ciliated tentacles around the mouth

24. The Coelomates: Protostomes, II Phylum: Mollusca (snails, slugs, squid, octopus, clams, oysters, chiton) Soft body most protected by a hard shell of calcium carbonate Foot (movement), visceral mass (internal organs); mantle (secretes shell); radula (rasp- like scraping organ) true coelem increases complexity & specialization of internal organs

25. There are 3 types of mollusks: Gastropods: sea slugs, snails and slugs Bivalves: clams, oysters, mussels, and scallops (2 hinged shells) Cephalopods: built for speed and motility, include squid and octopi; have sophisticated sense organs.

26. Class Cephalopoda squids, octopus, cuttlefish, nautilus

27. The Coelomates: Protostomes, III Phylum: Annelida (earthworms, leeches, marine worms) True body segmentation (specialization of body regions) Closed circulatory system Metanephridia: excretory tubes “Brainlike” cerebral ganglia Hermaphrodites, but cross- fertilize leech fan worm

28. The Coelomates: Protostomes, IV Phy: Arthropoda trilobites (extinct); crustaceans (crabs, lobsters, shrimps); spiders, scorpions, ticks (arachnids); insects (entomology) 2 out of every 3 organisms (most successful of all phyla) Segmentation, hard exoskeleton (cuticle)~ molting, jointed appendages; open circulatory system (hemolymph); extensive cephalization

29. Arthropod groups insects 6 legs, 3 body parts crustaceans gills, 2 pairs antennae crab, lobster, barnacles, shrmp arachnids 8 legs, 2 body parts spiders, ticks, scorpions

30. The Coelomates: Deuterostomes, I Phylum: Echinodermata (sea stars, sea urchins, sand dollars, sea lilies, sea cucumbers, sea daisies) Spiny skin; sessile or slow moving Often pentaradial Water vascular system They are radially symmetrical as adults, and bilateral as larvae.

31. Water Vascular System Madreporite stone canal ring canal radial canal lateral canals Ampulae tube feet