Overview of Animal Diversity

31.1 Animals are multicellular heterotrophs without cell walls.Some General Features of Animals

• Animals are multicellular heterotrophs that are diverse in form and habitat, are mobile, reproduce sexually, and have characteristic embryonic development. (p. 618)

31.2 Animals are a very diverse kingdom.The Traditional Classification of

Animals• Taxonomists have traditionally created phylogenies by comparing anatomical features and embryological development. (p. 620)

• Kingdom Animalia is traditionally divided into the

Parazoa lack a definite symmetry and organized tissues.

Eumetazoa have a definite symmetry and organized tissues. (p. 620)

• The eumetazoan branch is divided into Radiata and

Bilateria -having bilateral symmetry. (p. 620) • Bilateral animals further split into groups with and without a body cavity (coelom). (p. 620)

This is a distinction long used for classification

Types of Body Cavitiespg 625

• Acoelomate -no body cavity– flatworms

• Pseudocoelomate-pseudocoel located between mesoderm and endoderm– roundworms, rotifers

• Coelomate- body cavity completely contained within mesoderm– many members inc Homo sapiens

Protostome/ Deuterostome• Protostome-

– Spiral Cleavage– Determinate Devo– Blastopore (invagination of blatula) becomes mouth

• Deuterostome– Radial Cleavage– Indeterminate Devo (stem cells)– Blastopore becomes anus

Segmentation

• Each segment may have full set of organs– Life may continue if a segment is injured– Facilitates more complex locomotion

• 32.3 Acoelomates are solid worms that lack a body cavity.

– Flatworms (platyhelminthes), simple body structure with ability to regenerate lost parts- (page 642)

• 32.4 Pseudocoelomates have a simple body cavity.The Pseudocoelomates• In the pseudocoelomates, circulation occurs in a pseudocoel, not in a defined circulatory system. (p. 646) – Nematodes-ex: parasitic Trichenella (raw pork)

(page 647)

• Puzzles related to Animal Evolution

• "Evo-Devo" and the Roots of the Animal Family Tree

• Origin of sponges?– The multinucleate hypothesis, the colonial

flagellate hypothesis, and the polyphyletic origin hypothesis all try to account for the origin of metazoans from single-celled protists. (p. 630)

• Puzzles related to Animal Evolution

• A large diversity of animal body plans occurred around the Cambrian period, with no new innovations since. (p. 630) Cause?...– the emergence of predatory lifestyles or geological

factors.– debut of Hox genes within developing animal embryos.

(p. 630)

INVERTEBRATES

• 33.1 Mollusks were among the first coelomates.Mollusk Body Plan• The evolution of a coelom was a significant advance in animal body structure because it repositions fluid and allows complex tissues and organs to develop. (p. 652)

• The molluscan body plan is bilaterally symmetrical, with an efficient excretory system and a muscular foot for locomotion. (p. 653-4) Many have rasping (scraping) tongue called radula.

• Major Classes of Mollusks• Major classes of mollusks include the class Gastropoda (snails and slugs), class Bivalvia (bivalves), and class Cephalopoda (octopuses, squids, and nautiluses). (pp. 656-657)

33.2 Annelids were the first segmented animals.Segmented Bodies

• • Segmentation was a key transition in animal body plans, because similar segments can be individually controlled for different functions. (p. 658) • Three principal features of annelids are repeated segments, specialized segments, and connections between segments. (p. 658)

• Tube within a tube body plan. (p. 658) • Locomotion --hydrostatic skeleton forces fluid from one segment to the next. (p. 658) Major Classes of Annelids• 12,000 species , three classes: – Polychaeta (polychaetes), Oligochaeta (earthworms),

and Hirudinea (leeches). (pp. 660-661)

33.3 Lophophorates appear to be a transitional group.

Lophophorates• The marine phyla Phoronida (phoronids),

Ectoprocta (bryozoans), and Brachiopoda (brachiopods) are characterized by a ridge around the mouth bearing ciliated, hollow tentacles (lophophore) that functions in gas exchange and food collection. (pp. 662-663)

33.4 Arthropods are the most diverse of all animal groups.

Arthropod Body Plan

• Over two-thirds of all named species on the earth are arthropods. (p. 664)

…arthropod body plan

• Jointed appendages -- – legs, antennae, and mouthparts, and an

exoskeleton of chitin and protein used for protection and water loss prevention,

– most diverse phylum on the planet. (p. 664)

– Arthropods are segmented, with some segments fused into functional groups (ex: head, thorax) (pp. 665-666)

…arthropods

• The exoskeleton is secreted by, and fused with, the epidermis, and provides a hard surface for muscle attachment. (p. 666) • All arthropods have an open circulatory system; some have adaptations such as compound eyes, a respiratory system composed of tracheae, and an excretory system composed of Malpighian tubules. (pp. 666-667)

• Why must arthropods molt?

A Major Group of Arthropods: Crustaceans

• Most crustaceans (35,000 species) have two pairs of antennae, three types of chewing appendages, and various pairs of legs. (p. 668) • Crustaceans are found in marine, freshwater, and terrestrial habitats. (pp. 668-669)

Major Classes of Arthropods: Arachnids

• Arachnids (57,000 species) have a pair of chelicerae, a pair of pedipalps, and four pairs of walking legs. (p. 670) – Two major orders are Araneae (spiders) and

Acari (mites and ticks). (p. 670)

Major Classes of Arthropods: Centipedes and Millipedes

• Centipedes (class Chilopoda) and millipedes (class Diplopoda) are made of a head region followed by numerous similar segments. – Centipedes have one pair of legs per segment,

and millipedes have two pairs per segment. – (p. 671)

Major Classes of Arthropods: Insects

• Class Insecta is the largest group of organisms on the planet, living in nearly every possible habitat. (p. 672) • Most are relatively small, and contain three body sections: head, thorax, and abdomen, with three pairs of legs attached to the thorax, and one pair of antennae. (p. 674) • Most insects have compound eyes. (p. 674)

…insects

• Sensory hairs, tympanal organs (sense vibrations such as sound waves) and chemoreceptors all act as sense receptors in insects. (p. 675) • Many insects undergo either simple or complex metamorphosis. (p. 675)

• What are the stages of complete metamorphosis?

Echinoderms

• 33.5 Echinoderms are radially symmetrical as adults.Deuterostome Development and an Endoskeleton• Echinoderms are marine animals with hard calcium plates forming a true endoskeleton in young individuals. (p. 676)

Echinoderm Body Plan• All echinoderms are bilaterally symmetrical during

larval development, and become radially symmetrical as adults. (p. 678) • Echinoderms have a five-part body plan with a central, branched nerve ring and an endoskeleton composed of calcium-rich plates (ossicles). (p. 678) • Many echinoderms can regenerate lost parts, but in most of them, reproduction is sexual and external. (p. 679)

• Echinoderms have a water vascular system

– Water pressure fills tube feet which allows movement and feeding. They have enough strength to pull apart a clam shell, which I cannot do. Then they stick their stomach inside and start digesting.

• Major Classes of Echinoderms• There are six living classes of Echinoderms: Crinoidea (sea lilies and feather stars), Asteroidea (sea stars or starfish), Ophiuroidea (brittle stars), Echinoidea (sea urchins and sand dollars), Holothuroidea (sea cucumbers), and Concentricycloidea (sea daisies). (p. 680)

VERTEBRATES

• 34.1 Attaching muscles to an internal framework greatly improves movement.The Chordates• Four features characterize the chordates: (1) single, hollow nerve cord; (2) a flexible notochord present at some developmental stage; (3) pharyngeal pouches connecting the pharynx and the esophagus (gill slits in human

embryos); (4) a postanal tail at least during embryonic development. (p. 684)

• 34.2 Nonvertebrate chordates have a notochord but no backbone.The Nonvertebrate Chordates• Tunicates possess a notochord and a nerve cord as larvae, but look at them as adults! (p. 686) • Lancelets are fishlike marine chordates with a permanent notochord running the entire length of the dorsal nerve cord. (p. 687)

• 34.3 The evolution of vertebrates involved invasions of sea, land, and air.Characteristics of Vertebrates• Vertebrates -vertebral column instead of a notochord and a distinct head. (p. 688) • The history of the vertebrates -they invaded the sea and then the land. (p. 689)

Vertebrates are distinguished from other chordates

• Neural crest (page 688 and 1090-91)• Internal organs• Endoskeleton of bone or cartilage for size

and movement

• Fishes• Fish were the first vertebrates and are the most diverse and successful vertebrate group. (p. 690) • Key characteristics of fish include a vertebral column, jaws and paired appendages, gills, single-loop circulation, and nutritional deficiencies (which means they need to eat nitrogen). (p. 690)

• Sharks eventually became dominant sea predators, partially due to a skeleton composed of calcified cartilage. Sharks were also among the first vertebrates to develop teeth. (p. 695)

• What do you know about shark’s teeth?

• Bony fish -- ossification provided a strong base for muscle attachment and evolved in fresh water. (p. 696)

– swim bladder for buoyancy, – a lateral line sensory system, – and a gill cover (operculum) to permit water to

be pumped over the gills. (pp. 696-697)

• Amphibians• legs

• cutaneous respiration• lungs, pulmonary veins• partially divided heart. (p. 698)

• evolved from lobe-finned fishes. • Include frogs and toads, salamanders, and

caecilians. (pp. 699-701)

•Reptiles• Key characteristics of reptiles include the amniotic egg, dry skin, and thoracic breathing (expand ribcage). (p. 702)

• Turtles, lizards and snakes, tuataras, and crocodiles. (pp. 707-709)

•Birds• Modern birds retain many reptilian characteristics, but lack teeth and have vestigial tails. They are distinguished from living reptiles by feathers and the presence of a thin, hollow flight skeleton. (p. 710)

• Descended from dinosaurs

• Mammals• Hair, mammary glands, a placenta, heterodont dentition, the ability to digest plant material, keratinized hooves and horns, and flight capability (in bats). (pp. 714-716)

• The Orders of Mammals• Mammals were not common until dinosaurs disappeared. Modern mammals fall into one of three categories: monotremes, egg-laying mammals; marsupials, pouched mammals; and placentals. (pp. 717-718)

• 34.4 Evolution among the primates has focused on brain size and locomotion.Primates• Grasping fingers and toes and binocular vision are two features that allowed primates to flourish. (p. 720) • Modern prosimians include lemurs, lorises, and tarsiers, while anthropoids include monkeys, apes, and humans. (pp. 720-721) -Zaboomafoo from PBS

• Australopithecines• Bipedalism marked the beginning of hominid evolution, although the reason for such evolution remains controversial. (p. 722)

• What are some possible reasons?• Maybe it’s just so we can hold hands.

• The Genus Homo• The first humans (Homo habilis) evolved from australopithecine ancestors about 2 MYA. (p. 724) • Homo erectus replaced H. habilis, and is believed to have come out of Africa. (pp. 724-725)

• Homo sapiens is both the only surviving species of the genus Homo and the only surviving hominid. (p. 726) • Humans are the only animals that can effectively make tools, that have refined and extended the ability to use conceptual thought, and that can use symbolic language and shape concepts and experiences with words. (p. 726) …but, Think Tank in National Zoo...

Taung Skull2.5 myo

Australopithicus afarensis

Taung Skull Site

Human Evolved from Monkey?

• If humans did evolve from monkeys (or gorillas) or anything from this chart, how would this change the phylogenic tree?