Animal Evolution (Learning Objectives) 1. Review the characteristics of organisms of the Kingdom Animalia 1 2. Recognize the evolution of animals as diploid multi-cellular aquatic organisms from a colonial protist. 3 Summarize the highlights of animal evolution and the order of their 3. appearance. Learn the names of the classification groupings that arose from successive adaptation with examples. 4 Learn the distinguishing features of each of the animal phylla and 4. identify its representative organisms. 5. Summarize the highlights of evolution of land animals from their aquatic ancestors and the order of their appearance appearance. 6. Recognize parasitism as an integral part of animal evolution. Learn the names of parasites causing common diseases and relate them to their classification grouping and is evolutionary features features. 7. Place any of the organisms learned in class or lab into its classification grouping , relate to others, and provide its evolutionary features. 8 Order 8. O d organisms i according di tto th the order d off th their i appearance on earth. th

Evolution of Animals Animals are eukaryotic, multi-cellular, heterotrophic organisms that ingest their food

The ancestor of animals was probably a colonial, flagellated protist whose cells gradually became more specialized and layered Somatic cells

Digestive cavity

Reproductive cells 1

Colonial protist,2 an aggregate of identical cells

Hollow sphere 3 Beginning of cell4 of unspecialized specialization cells (shown in (cross section) cross section) ti )

Infolding 5 (cross section)

Gastrula-like “proto-animal” (cross section)

Animal Diversity E k Eukaryotic ti Kingdom Ki d Animalia – Body composition • Multi-cellular evolving from a colonial protist ancestor • Later forms with organ systems, organs, and tissues

– Heterotrophic p • Some free living others parasitic

– Early forms are aquatic – Evolutionary adaptations led to evolution of land animals

Chordates

Echinoderms E

Arthropods

Annelids

Molluscs

Flatworms

Cnidarians

Sponges

Round worms R

Segmentation Mouth from First Embryonic Opening

No Body y Cavity y (No coelom)

Mouth from Second Embryonic Opening

Organ Systems (Coelom) Body y Cavity y (Pseudocoelom) Tube w/in Tube

Radial Symmetry

Bilateral Symmetry

Sac Body Plan Multicellular

Level of Organization

Phylogenetic Tree of Animals Mostly invertebrates

Deuterostomes

Radial symmetry No true tissues

Protostomes Bilaterians Bilateral symmetry

Eumetazoans True tissues

Ancestral colonial protist

Nematodes

Arthrop pods

Anne elids

Mollu uscs

Flatwo orms

Chorda ates

Echinoderrms

their common names)

Cnidaria ans

Phylla (by

Spong ges

Invertebrates & Vertebrates

Two o major ajo a animal a body forms: o s Early a y Invertebrates and later Vertebrates • Steps of animal evolution – Formation F ti off tissues ti – Body made of three distinct layers of cells – Body symmetry: radial and bilateral – Bilateral organisms: • Deuterostomes & protostomes

Classification Criteria for Animals Level of Organization Tissue organ, Tissue, organ organ systems Body Symmetry None- asymmetric None Bilateral Radial Body Plan Sac with one opening T b within Tube ithi a ttube-two b t openings i Segmentation (with and without appendages)

Key

Haploid (n) Sperm

Diploid (2n)

2

1 Meiosis

Egg

Zygote (fertilized egg)

3

Diploid cells Eight-cell stage

Adult 8 Metamorphosis Digestive tract

4

Blastula (cross section)

Ectoderm Larva

5

7 Endoderm Internal sac

Later gastrula (cross section)

Early gastrula Future (cross section) 6 mesoderm

Animal development may include a blastula, gastrula, and larval stage

Animals can be characterized by basic features of their “body plan”. They may vary in symmetry. symmetry Top

Dorsal surface

Anterior end

Posterior end Ventral surface Bottom

Animals and digestive cavities Incomplete gut (sac-like) radial symmetry bilateral symmetry Complete gutgut type 1 bodies without shells bodies with shells bodies with segments with exoskeleton Complete gut- type 2 hydraulic tube feet bodies with notochord

Deuterostomes

Radial symmetry No true tissues

Protostomes Bilaterians Bilateral symmetry

Eumetazoans True tissues

Ancestral colonial protist

Nematodes

Arthrop pods

Tube 2: openings

Anne elids

Mollu uscs

Flatwo orms

Chorda ates

Tube: 2 Sac like openings

Echinoderrms

Cnidaria ans

Animal guts

Spong ges

Sac like

INVERTEBRATES Sponges have a relatively simple, porous body Sponges are the simplest animals and have no true tissues

S Sponges filt filter ffood d ffrom th the water t passing i th through h the porous body

Cnidarians are radial animals with tentacles and d stinging ti i cells ll and d ttrue tissues ti They have two body forms - Polyps, such as hydra - Medusae, the jellies

Hydra

Jellyfish

Sea anemone

Animal body cavity-coelom

Tissue-filled region (from mesoderm) Body covering (from ectoderm)

Flat wormsworms none Digestive tract (from endoderm)

Body covering (from ectoderm) Muscle layer (from mesoderm)

Round worms- pseudo coelom

Digestive tract (from endoderm) Pseudocoelom

Coelom

Round worms- coelom Digestive tract (from endoderm)

Body covering (from ectoderm)

Tissue layer y lining coelom and suspending internal organs (from mesoderm)

Flatworms are the simplest bilateral animals Flatworms are bilateral animals that have: - no body cavity - a sac-like gut - a simple nervous system - Free living & parasitic forms Gastrovascular G t l cavity

N Nerve cords d

Mouth

Eyespots Nervous tissue clusters

Bilateral symmetry

Tapeworms Cause diseases commonly after eating raw or undercooked meat (beef and pork) or fish that contains the immature form of the tapeworm

Parasitic flatworms e.g. Flukes and tapeworms p Flukes diseases - sheep and cattle (fascioliasis)

Colorrized SEM 80 0

- Human lung fluke disease (endemic hemoptysis)

Units with reproductive structures

Scolex Hooks (anterior Sucker end))

Parasites form a large proportion of the diversity of life on earth -Have a complex life cycles with more than one host

Round R d worms (Nematodes) (N d ) • have a pseudocoelom and a • complete digestive tract and are • covered by a protective cuticle. • usually microscopic and colorless. • some live free in moist soil, water, or in decaying matter. • Parasitic forms cause diseases of plants and animals.

Parasitic- with Parasitic complex life-cycle

Free-living

LM 350

Mouth

Colorized S SEM 400

Muscle tissue Trichinella juvenile

Molluscs- have a distinct body plan • bilaterally symmetrical • a muscular foot, visceral mass, and a mantle which may secrete a shell • well-defined well defined organ systems: circulatory circulatory, respiratory, respiratory and digestive with a rasping radula Visceral mass Coelom Heart Kidney Mantle Mantle cavity Anus

Reproductive organs Digestive g tract Shell Radula

Gill

Mouth Foot Nerve cords

Digestive tract Radula Mouth

The largest g group g p of molluscs includes the snails and slugs

Another group of molluscs are the bivalves have shells divided into two halves. This includes clams, oysters, mussels, and scallops

Another group g p are adapted p to be agile g predators p such as squids and octopuses

Annelids (Segmented worms) – Segmentation S t ti provides id added dd d mobility bilit ffor swimming i i and burrowing Earthworms eat their way through soil and have a Segment wall closed circulatory system (partition Anus

Epidermis Circular muscle

between segments) t )

Segment wall g Longitudinal muscle Dorsal vessel

Mucus-secreting organ

Excretory organ

Intestine Bristles

DorsalCoelom vessel Digestive tract Brain

Bristles ExcretoryNerve cord Ventral vessel organ Segment a wall Blood vessels

Mouth

Nerve cord Pumping segmental vessels

Giant Australian earthworm

The largest group of segmented worms search for prey on the seafloor or live in tubes and filter food particles

Arthropods (Jointed legs) – segmented animals – jjointed appendages pp g Cephalothorax Abdomen – exoskeleton Thorax A t Antennae – Extremely Head (sensory reception) diverse

Swimming appendages

Walking legs Pincer (defense)

Mouthparts (feeding)

Di Diverse arthropods th d iinclude: l d - Millipedes and Centipedes - Horseshoe crabs - Arachnids such as spiders, scorpions, mites, and ticks - Crustaceans- aquatic. Include crabs, shrimps, and barnacles - Insects

Colo orized SEM 90 00

A black widow spider (about 1 cm wide))

A scorpion (about 8 cm long)

A dust mite (about 420 µm long)

Echinoderms have spiny skin, an endoskeleton, d k l t and d a water t vascular l system t for movement - organisms such as sea stars and sea urchins - radially symmetrical as adults Tube foot

Tube foot

Spine

The water vascular system has suction cup– like tube feet used for respiration and locomotion Anus Spines

Stomach

Tube feet Canals

Phylum Chordata, is distinguished by four f t features • • • • •

A dorsal hollow nerve cord A stiff tiff notochord t h d Pharyngeal slits A muscular post-anal tail Includes invertebrates and verebrates

Ma ammals

Reptiles R

Am mphibians

Craniates Vertebrates Jawed vertebrates Tetrapods Amniotes Lo obe-fins

Ray-fiinned fishe es

Sha arks, rays

Lampreys

Ha agfishes

La ancelets

Tunicates

Chordates

Amniotic egg Legs Lobed fins Lungs or lung derivatives Jaws

Vertebral column Head

Invertebrates

Brain

Ancestral chordate

Milk

Ch d t Chordates

The simplest chordates are tunicates and lancelets Marine invertebrates with p pharyngeal y g slits for suspension feeding Excurrent siphon

Post-anal tail Dorsal, hollow nerve cord

Head

Pharyngeal slits Mouth

Muscle segments Notochord

Adult Ad lt (about 3 cm high)

Larva

Notochord

Mouth

Pharynx Pharyngeal slits Digestive tract Water exit Segmental muscles Anus

Dorsal, hollow nerve cord Post-anal tail

Jawless fishfish Lampreys are vertebrates that lack hinged jaws and paired fins

Sharks and rays y have a flexible skeleton made of cartilage Uncovered gills

Bony Fishes (ray-finned fishes) - skeleton k l t reinforced i f d with ith a h hard d matrix t i off calcium phosphate - Operculi that move water over the gills - A buoyant swim bladder Bony skeleton Gills

Operculum Pectoral fin Heart Rainbow trout, trout a ray-fin

Dorsal fin

Anal fin Swim bladder Pelvic fin

Lobe-fins L b fi fifishes h have h muscular l fifins supported by bones

Amphibians are tetrapods—vertebrates with two pairs of limbs allowing movement on land

Bones supporting gills

Tetrapod limb skeleton

Most amphibian reproduce in water Fertilization and embryos and larval development take place in water E Examples l are ffrogs, toads, t d and d salamanders

Reptiles are amniotes—tetrapods with a terrestrially adapted egg Terrestrial adaptations of reptiles include Waterproof p scales Internal fertilization shelled, amniotic egg

Dinosaurs, the most diverse reptiles to inhabit land – Included some of the largest animals ever to inhabit land – May have been endothermic, producing their own body heat

Birds are feathered reptiles with adaptations for flight Birds evolved from a lineage of small, two-legged ectothermic dinosaurs called theropods. Living reptiles other than birds are ectothermic Wing claw (like dinosaur)

Long g tail with many vertebrae (like dinosaur)

Teeth T th (like dinosaur)

Feathers

Birds have wings, feathers, endothermic metabolism and many other adaptations related metabolism, to flight

Mammals are endothermic amniotes with - Hair for temperature insulation - Internal fertilization - Mammary glands for milk production Two groups of mammals 1. Marsupials- Kangaroos 2. Eutherians, placental mammals

The embryos of marsupials are: - nurtured within the uterus - leave the uterus before completing development -complete development attached to the mother’s nipple, usually inside a pouch

Eutherians, placental mammals, complete development before birth