The Evolution of Animal Diversity What Characteristic

The Evolution of Animal Diversity

What Characteristic Define an Animal? • Eukaryotic cells • Multicellular • Ingestive Heterotroph

Other Common Characteristics of Animals • Lack cell walls • Sexual reproduction • Diploid, except for gametes • Excitable (nervous & muscular) tissue • Similar embryology (blastula & gastrula)

Early embryonic development

Early embryonic development blastula gastrulation

Animal Diversity

How did the animal kingdom evolve? - Oldest fossils are 700 million years old -Animals probably evolved from an ancestor of a colonial choanoflagellate protist

One hypothesis for the origin of animals

Major Trends in Animal Evolution: • Development of Tissue Layers • Patterns of Body Symmetry • Development of a Body Cavity • Body Segmentation

Major Trends in Animal Evolution: Development of Tissue Layers Most animals have tissues that arise from three embryologic tissues layers: • Ectoderm – produce skin and nervous system • Endoderm – produces GI tract • Mesoderm – produces muscle, skeleton and most organs

Three embryologic tissue layers Ectoderm Endoderm Mesoderm

Major Trends in Animal Evolution: Patterns of Body Symmetry • Asymmetrical • Bilateral symmetry • Radial symmetry

Body symmetry Radial = any cut through main body axis produces mirror image halves Bilateral = a cut through main body axis produces right-left halves

Major Trends in Animal Evolution: Development of a Body Cavity: • Allows independent movement of body wall • Cushions internal organs • Provides a hydrostatic skeleton • Increases flexibility and mobility

Major Trends in Animal Evolution: Development of a Body Cavity: • Coelomate – true body cavity fully lined with mesoderm • Pseudocoelomate – body cavity in direct contact with gut • Acoelomate – lack body cavity

Acoelomate Pseudocoelomate Coelomate

Coelomates: Protostomes VS Deuterostomes Protostomes: mesoderm forms from mass of cells between endoderm and ectoderm Deuterostomes: mesoderm forms as outpocketing of gastrulation cavity

Protostomes Deuterostomes Visualizing Protostome & Deuterostome Development

Major Trends in Animal Evolution: Body Segmentation • Most animals have segmented bodies • Segmentation increases body flexibility and mobility

Forms of asexual reproduction • fission: splitting off of new individual from existing one, parent cell divides into two parts • budding: new individual grows from body of original, can detach (solitary lifestyle) or remain attached (colonial lifestyle) • fragmentation: breaking of the body into several pieces, each of which forms a complete adult (aka regeneration) • gemmulation: release of specialized groups of cells that are enclosed in a capsule and grow into new individuals

Sexual Reproduction • Two haploid gametes (produced by meiosis) fuse to form a diploid zygote. • female gamete = ovum = unfertilized egg; usually large and non-motile cell. • male gamete = spermatozoan = small, usually flagellated cell. • Fertilization occurs in two ways: – external fertilization -eggs & spermatozoa are shed into the environment. – internal fertilization -sperm are deposited or near the female’s reproductive tract and egg and sperm unite within the female’s body.

Phylogenetic tree of Kingdom Animalia

Phylum Porifera: Sponges Probably first animals to evolve – similar to modern colonial choanoflagellate protist

Early embryonic development

What was the distinguishing characteristic that differentiated a true multicellular organism and a colonial protist?

Sponges have specialized cells that exhibit cellular recognition but lack true tissue layers Osculum Epithelial cells Porocyte cell Noncellular mesoglea and skeletal components Anatomy of a Sponge Choanocytes – specialized for obtaining food Ameobocytes- specialized for digestion, nutrient transport, waste disposal, skeletal component manufacure. Can change into other cell types.

Sponges can reproduce sexually or asexually Sponges are hermaphrodites, producing both sperm and eggs.

Sexual Reproduction Motile sponge larva Newly settled sponge

Asexual Sponge Reproduction 1. Budding 2. Gemmules Sponge Reproduction

Sponge Classes • Demospongae (spongin) • Calcarea (Ca) • Hexactinella (Si)

Major Trends in Animal Evolution: 1. Evolution of tissue layers

Phylum Cnidaria Coelenterata): Hydra Jellies Anemones Corals

Phylum Cnidaria Characteristics: • Radial symmetry • True tissue layers (but only 2, not 3) • Cnidocytes/nematocysts (stinging cells) for prey capture • Gastrula stage of development • Digestive (gastrovascular) cavity • Diversity of Living Things: Phylum Cnidaria • Phylum Cnidaria (Jellyfish, Sea Anemones, Corals, Sea Combs) • Phylum Cnidaria: The Stinging Animals

• Nerve Net, with nerve cells, but not centralization/brain • Excretion of water through specialzed cells • Both extracellular and intracellular digestion • One opening -2 way digestive system • Dioecious • Planula/ciliated larvae

Radial symmetry allows a sessile animal to meet its environment equally from all sides Arms & Camp, 1995

Early embryonic development blastula gastrulation

Polyp and medusa forms of cnidarians Medusa Polyp Purves et al. , 1992

Cnidocytes and nematocysts Firing Nematocysts Brum et al. , 1994

For jellies and hydra: For anemones and corals: A comparison of poriferans & cnidarians

Coral reefs have enormous biodiversity.

Zooxanthellae

Cnidarian Classes • Hydrozoa fresh water hydras • Anthozoa sea anemones, corals • Siphonphora Portuguese Man-A-War • Scyphozoa jellyfish Life Cycle of a Cnidarian Jellyfish, Coral Feeding, Coral Spawning, 2, Moon jelly

Ctenophora “comb jellies” “sea walnuts” • • Radially symmetrical w/ mesoglea Eight rows/ “combs” of banded cilia that propel No polyp stage Hermaphroditic

Major Trends in Animal Evolution: 1. Evolution of tissue layers 2. Evolution of bilateral symmetry

Bilateral symmetry Only one plane of symmetry that produces mirror-image halves Cephalization: evolutionary trend toward concentration of sensory structures at the anterior end Arms & Camp, 1995

• • Triploblastic- 3 embryonic layers Ectodermskin, nervous structures Endoderm- digestive tract, reproductive Mesoderm - muscles, skeleton, body systems

Hallmark characteristics of flatworms: • Bilateral symmetry • Three tissue layers • Acoelomates – solid bodies without a body cavity

Phylum Platyhelminthes · flat, thin body and there are no spaces between tissue layers therefore no cell is far from the environment, diffusion for circulation and respiration · most primitive animals w/ bilateral symmetry · bilateral symmetry allow for further specialization w/ a dorsal and ventral end, anterior and posterior end, allows organism to respond more immediately to environment · "brain"-collection of nerve cells at anterior end • "cephalization" tendency towards brain formations • Kingdom Animalia: Phylum Platyhelminthes • Phylum platyhelminthes: The Flatworms

Acoelomates

Solomon et al. , 1996 Cestoda (tapeworms) Trematoda Walls, 1982 Turbellaria (free-living flatworms) Walls, 1982 (flukes)

Class Turbellaria: • • • free living, planarians eyespot, cilia over body surface predatory/saprophytic one digestive opening located ventrally medial, extendable pharynx attached to mouth branched digestive tract/glands sexual and asexual reproduction: hermaphroditic & regeneration flame cells for water excretion & nitrogenous wastes 2 main nerves w/ side braches no resp sys, gas exchange through surface and environment Basic Anatomy of a Planarian

Internal anatomy of free-living Planaria flat worm Arms & Camp, 1995 Gastrovascular cavity

Class Trematoda: Flukes • • VD. LS. 4. 11. 14516 Life Cycle -internal/external parasites -attach to host w/suckers -protective cuticle -asexual reproduction of larvae in snail -sexual reproduction of fluke in sheep -have a digestive system Blood Fluke Life Cycle

Figure 33. 10 The life history of a blood fluke (Schistosoma mansoni) Trematoda-parasitic flukes Endo-parasites of vertebrates, have at least 2 hosts (complicated life cycles) Blood fluke -get from being in water with snails and sewage Liver fluke- if eat uncooked fish Lung fluke-if eat uncooked crab

Class Cestoda: Tapeworms • no brain or "head" • scolex (w/ hooks & suckers) for attaching to intestine • self reproduction organs (hermaphroditic) • repeating units called proglottids • larva consumed by 1 st host, encyst in muscle, 2 nd host consumes muscle & adult form in • intestinal tract

Cestoda-tapeworms Endoparasites of vertebrates. Head region (scolex) is modified for attachment inside intestine. No digestive system Proglottids produce male and female gametes at same time, create fertilized eggs that pass out with feces. Host gets infected by eating food contaminated with eggs, (or putting contanimated fingers in mouth).

Major Trends in Animal Evolution: 1. Evolution of tissue layers 2. Evolution of bilateral symmetry 3. Development of a pseudocoelom

Phylum Nematoda: roundworms Animations: Videos: Intestinal Worms, Schistomasis Filariasis, Filiarasis, Threadworms

Hallmark characteristics of roundworms: • Three tissue layers • Bilateral symmetry • Pseudocoelom • Complete digestive tract – one way passage of nutrients from mouth to anus

Major Trends in Animal Evolution: 1. Evolution of tissue layers 2. Evolution of bilateral symmetry 3. Development of a pseudocoelom 4. Development of a true body cavity: coelom

What the significance of coelom lined with mesoderm? Pseudocoelomate Coelomate

Phylum Mollusca: Soft Bodied Animals · Head/foot w/ sensory and motor organs · Visceral mass w/ well developed organs of digestion, excretion and reproduction · Mantle which encloses visceral mass and secretes the shell · Respire through gills & mantle · Radula is a movable tooth like chitinous strip · Ca. CO 3 shell · 3 chambered heart, open circ system • siphon • N wastes removed through nephridia • Kingdom Animalia: Phylum Mollusca • Phylum Mollusca (Mollusks) • Mollusks : Mollusks, such as squids and octopuses are explored in this video segment. • Visualizing Movement in Mollusks • Mollusks Facts and Fun

Phylum Mollusca gastropods cephalopods pelecypods

All mollusks have a similar body plan:

Class Gastropoda • univalves; snail & slugs, abalones, limpets. Feeding Gastropod VD. LS. 4. 11. 20156 Radula, octopus • mantle which secreted shell (layer of cells) • radula, rasping feeding device • muscular foot • gills for gas exchange w/i mantle which absorbs O 2 from H 2 O • land varieties can have a lung • open circulatory system, tissues bathed in blood Hemocyanin=blue • trochophore larvae • Leopard Slug Mating , Nudibranch

Class Pelecypoda • bivalves: clams, mussels, oysters, scallops • no radula • have 2 shells controlled by adductor and abductor muscles • incurrent and excurrent siphon Not Just for Chowder

Class Cephalopoda • octopus, squid, nautilus, cuttlefish • shell b/co internal (xcept nautilus) • foot evolves into flexible arms • closed circulatory system for more efficient travel to muscles • siphon used in locomotion Octopus Camouflage 2 Mimic Octopus Hatching & Learning Giant Squid

Major Trends in Animal Evolution: Development of segmentation

Phylum Annelida Earthworms- terrestrial worm movement Polychaetes – marine segmented worms swimming Leeches

Segmentation: The combination of a true coelom that acts as a hydrostatic skeleton and segmentation allows for controlled directed movements. • A skeleton gives muscles something to contract against and allows coordinated movement. • Segmented circular muscles along with longitudinally directed muscles allows forward directed movements.

Phylum Annelida · Coelomate: w/ all organs suspended in the body cavity by an attached membrane “peritoneum” · Have a closed circulatory system w/5 hearts which pump blood through ventral vessel and blood returns to heart through dorsal blood vessel · Segmented repeating body parts: metamerism evolutionary advantage: an animals can increase in size by adding segments and the segments can become specialized · Locomotion through unsegmented body parts • Body= respiratory surface (can use gills) • Earthworm Systems • Ecological Importance of Annelids

Class Polychaetes (greatest variety in annelids) • Marine, can reach up to 3 meter VD. LS. 4. 11. 16756 Sand Mason Worm • can be free moving or sedentary • Can have antennae and jaws • Have parapodia w/ setae VD. LS. 3. 20. 36231 Sea Mouse • can have external gills • Peritoneum-mem. from inner mesoderm holding organism place • Trochophore larvae: w/ apical tuft, girdle of cilia and mouth • Marine Worms, Plumed Worm

Class Oligochaetes • Digestion: food, mouth, pharynx, crop, gizzard, intestine • Excretion: anus and nephridia for N wastes • Locomotion: muscle groups & 2 prs or 4 setae per segment, also to grip earth • Reproduction: hermaphroditic, clitellum

Class Hirudinea • leeches VD, LS. 4. 12. 23455 Locomotion • Free living and parasitic • Parasitic species have rasping teeth • secrete hirudin, an anticoagulant NOVA Now Leeches Giant Leech

Major Trends in Animal Evolution: Development of jointed appendages

Phylum Arthropoda: Arthropod = “jointed foot” Jointed appendages and a hard exoskeleton has made arthropods the most successful phyla of animals.

Exoskeleton • chitinous exoskeleton (a cuticle secreted by underlying epidermis that contains chitin) chitin is a polysacchride also found in the cell walls of fungi • the exoskeleton serves as an armor to protect the soft body of the insect, as well as to aid in mobility • this outside skeleton must be shed periodically as the athropod grow the shedding is called “ecdysis”

External skeleton made of chitin allowed the arthropods to inhabit the land: • protection • waterproofing • anchor site for attachment of muscles Disadvantage of an exoskeleton : • most be shed to allow growth (molt) • restricts movements around joints • limits ultimate size of the organism (heavy)

Metamorphosis • growth accompanied by ecdysis (molting) of the exoskeleton, can become 33% larger than before the shed Incomplete Metamorphosis • Can grow by complete or incomplete metamorphosis • Butterfly emerging Complete Metamorphosis

Introduction to Arthropods · arthro-joint pes-foot (greek) · largest phylum, most successful & ubiquitous, 3 x's all other animals species · coelomate · exoskeleton w/ chitinous (polysaccharide) plates & hinges which must be shed · muscles attached to inner exoskeleton · molting necessary, many larval stages, complete & incomplete metamorphosis · loss of metamerism: segments fused · segmental structures (appendages) b/co struct & fnctally diff. Arthropods Videos

· modified head, thorax and abdomen (cephalothorax) · nervous sys. w/ dorsal ant. brain -> ventral nerve cord w/ ganglionic swellings in each segment · open circ system, tissues bathed in blood · dioecious • 5 senses: compound & simple eyes, taste, smell through pheromones, touch, hearing

Horseshoe crab, Limulus polyphemus Orb spider, Araneus quadratus House dust mite, Dermatophagoides sp. Emperor scorpion, Pandinis imperator Phylum Arthropoda: Subphylum: Chelicerata Solomon et al. , 1996

Phylum Arthropoda: Subphyla Aquatic Mandibulates Class: Crustacea Krill http: //members. aol. com/iq 3 d 2/deep_sea/Hi_Res/Krill. jpg Mantis shrimp larva Gooseneck barnacle Brum et al. , 1994 Pink fairy crab David Doubilet; National Geographic, Jan 1999

Subphyla Aquatic Mandibulates Class Crustacea • Carapace that covers head and thorax, 6 segments in abdomen • Respires through gills • N wastes excreted through green gland • crayfish, crabs, lobsters, shrimp, Daphnia, pillbugs, barnacles, prawns

Phylum Arthropoda: Uniramia Diplopods: Millipede Praying mantis Campbell et al. , 1999 Potter 1982 Insecta Greater stag beetle, Lucanus cervus Potter 1982 Chilopods: House centipede, Scutigera coleoptera

Subphyla Terrestrial Madibulates/Myriapods Class Diplopoda • "millipedes" • range from 2 mm - 28 cm • have mandibles for chewing decaying vegetation • 2 pairs of legs per segment adapted for burrowing

Subphyla Terrestrial Madibulates/Myriapods Class Chilopoda • "centipedes" • range from 3 -30 cm • have fangs, are predacious carnivores some species consume frogs, birds snakes and mice • 1 pair of legs per segment, adapted for running • appendages on last segment used for defense not locomotion

Insecta • Insecta – – • • 70% of all animals on earth 30 orders: Diptera: “ 2 wings”flies, gnats, mosquitoes Coleoptera: “shield wings”beetles Hymenoptera: “membrane wing”bees, wasps, ants Lepidoptera: “scale wing” moths & butterflies 3 Body Sections 3 prs of legs per thorax 1 pr antennnae excrete N through Malpighian tubules eliminated in dry uric acid crystals • respire through tracheae and spiracles • Complete & Incomplete Metamorphosis • Parthenogenesis

Harmful Insects • Pests, vectors of pathogens, crop eaters, sting, bite Botfly, Bed Bugs

Beneficial Insects • Pollination, honey, silk, food (entomophagy), biological control, designer genes Eating Machines Medicinal Maggots Forensic Entomology Crime Scene Creatures

Major Trends in Animal Evolution: Development of a body cavity from the gastrulation cavity: deuterostome coelomates

Protostomes Deuterostomes

Coelomates: Protostomes VS Deuterostomes Protostomes: mesoderm forms from mass of cells between endoderm and ectoderm Deuterostomes: mesoderm forms as outpocketing of gastrulation cavity

• Deuterostomes (echinoderms and chordates) develop the anus first, then the mouth at the other end of the embryo. Deuterostomes are coelomate animals these embryological characteristics: – Radial cleavage in embryonic cell division: the daughter cells sit on top of previous cells. – Fate of cells is indeterminate; if embryonic cells are separated, each one develops a complete organism. – The blastopore is associated with the anus, and the second embryonic opening is associated with the mouth.

Phylum Echinodermata Sea star Sea urchin Brittle star Sea Lily

Echinoderms: • All are marine organisms • Larvae are bilaterally symmetrical • Adults are slow moving or sessile and have petamerous radial symmetry (although they are not perfectly symmetrical) • Embryologic development makes them more similar to chordates than to the cnidarians • Visualizing an Echinoderm

• Unique to echinoderms is the water vascular system, a network of hydraulic canals branching into extensions called tube feet. – These function in locomotion, feeding, and gas exchange.

Echinos=spiny Derma=skin Echinoderms include : sea star, sea urchin, sea cucumber, sand dollar, basket stars brittle stars · marine & largely bottom dwellers · pentamerous radial symmetry, from bilateral ancestor · internal skeleton w/calcareous ossicle that may articulate, bears projecting spines/tubercles · series of canals, water vascular system · no excretory organs • mostly dioecious w/ external fertilization • Fertilization in a Sea Urchin

Echinoderm Classes • Asteroidea: star shaped, free moving, with bodies composed of rays • Ophiuroidea: basket stars, serpents stars, brittle stars • Echinoidea: sea urchins, sand dollars – Fertilization • • • Holothuroidea: sea cucumber (anus) Crinoidea: Sea lillies, feather stars Colentricycloidea: sea daisies Classes of Echinoderms Sea cucumber Fights with Guts

Protostomes Deuterostomes Coelomates Pseudocoelomates Acoelomates Bilateral symmetry Brum et al. , 1994

Primitive Chordates • Anatomy of a Tunicate

References • http: //cas. bellarmine. edu/tietjen/images/phylum_porifera. htm • http: //www. cartage. org. lb/en/themes/sciences/Zoology/Biologicaldiverstity/Animals II/Animals. II. htm • Parasites How They Live • Invertebrates Close Up • Animals webpage