Biology, Deutorostomes

Raven Biology 13th edition, Deutorostomes CH34

Phylum Echinodermata, Characteristics include

exclusively marine, deuterostomes with endoskeleton, pentaradial symmetry; includes sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers

Symmetry and Endoskeleton, Symmetry in echinoderms

pentaradial as adult, bilateral as larva; oral surface defines mouth; nervous system is nerve ring with branches; no centralization of function

Symmetry and Endoskeleton, Endoskeleton in echinoderms

epidermis covers endoskeleton; composed of calcium carbonate ossicles

Water-vascular System, Water-vascular system is

radially organized with radial canal extending from ring canal into each body branch; includes tube feet (may or may not have suckers)

Regeneration and Reproduction, Regeneration in echinoderms

many can regenerate lost parts; some reproduce asexually by splitting

Regeneration and Reproduction, Most reproduction in echinoderms is sexual

gonochoric; gametes released into water; free-swimming larvae

Class Asteroidea, Includes sea stars and sea daisies

important predators in many marine systems; most have 5 arms, some have multiples of 5

Classes Crinoidea & Holothuroidea, Class Crinoidea includes

sea lilies and feather stars

Classes Crinoidea & Holothuroidea, Class Holothuroidea includes

sea cucumbers

Class Echinoidea, Includes

sea urchins and sand dollars

The Chordates, Chordates are defined by having

a notochord, dorsal hollow nerve cord, pharyngeal slits, and post-anal tail at some stage

3 Chordate Subphyla, Urochordata (nonvertebrates) includes

tunicates and salps

3 Chordate Subphyla, Cephalochordata (nonvertebrates) includes

lancelets

3 Chordate Subphyla, Vertebrata includes

chordates with a spinal column

History of the Vertebrates, First vertebrates appeared in oceans about 530 MYA

jawed fishes soon became dominant; amphibians invaded land; reptiles became dominant land vertebrates; birds/mammals dominant after Cretaceous mass extinction

Fishes, Most diverse vertebrate group

over half of all vertebrates; provided evolutionary base for amphibian invasion of land

Fish Characteristics, Key features include

vertebral column (hagfish/lamprey exceptions), jaws and paired appendages (exceptions), internal gills, single-loop blood circulation, nutritional deficiencies

Major Classes of Fishes, Include

Actinistia (coelacanths), Dipnoi (lungfish), Actinopterygii (ray-finned fishes), Chondrichthyes (sharks, skates, rays)

Major Classes of Fishes, Also include

Petromyzonida (lampreys), Myxini (hagfishes), and extinct groups Placodermi, Acanthodii, Ostracoderms

Emergence of Sharks and Bony Fish, At end of Devonian pioneer vertebrates disappeared

replaced by sharks and bony fishes; first evolved in early Devonian (400 MYA); jaw improved to allow wider mouth opening

Class Chondrichthyes, Includes sharks, skates, rays

became dominant sea predators in Carboniferous; cartilage skeleton calcified with calcium carbonate granules for light, strong skeleton

Teeth and the Lateral Line System, Sharks were among first vertebrates to develop teeth

evolved from rough scales; easily lost but continuously replaced

Teeth and the Lateral Line System, Lateral line system

series of sensory organs under skin that detects changes in pressure waves

Shark Reproduction & Development, Eggs fertilized internally

most pups born alive; some lay fertilized eggs; long gestation and few offspring means slow recovery from population declines

Bony fishes, Evolved at same time as sharks (400 MYA)

adopted heavy internal skeleton of bone; most species-rich vertebrate group (>30,000 species); adaptations include swim bladder and gill cover

Class Amphibia, First vertebrates to walk on land

direct descendants of fishes

5 distinguishing amphibian features, Include

legs for land, lungs, cutaneous respiration, pulmonary veins, partially divided heart

Successful Invasion of Land by Vertebrates, Required adaptations

legs for support, lungs for air, redesigned heart, reproduction in water, system to prevent desiccation

Orders of Amphibians, Include

Anura (frogs/toads), Caudata (salamanders/newts), Apoda (caecilians)

Class Reptilia, Over 10,000 living species

exhibit three key features: amniotic eggs (watertight), dry skin (prevents water loss), thoracic breathing (increases lung capacity)

Major Orders of Reptiles, Include

Squamata (lizards/snakes), Rhynchochephalia (tuataras), Chelonia (turtles/tortoises), Crocodylia (crocodiles/alligators)

Major Orders of Reptiles (extinct), Include

Ornithischia (Stegosaur), Saurischia (Tyrannosaur), Pterosauria (flying reptiles), Plesiosauria, Ichthyosauria

Dinosaurs, Dominated for over 150 million years

became extinct 66 MYA (except bird descendants) likely from asteroid impact

All living reptiles are ectothermic, They obtain heat from external sources

regulate body temperature by moving in/out of sunlight; compare to endothermic animals that generate internal heat

Crocodiles and Birds, Crocodiles resemble birds more than other reptiles

build nests, care for young, have 4-chambered heart

Class Aves, Success lies in unique structure - feather

developed from reptilian scales; feathers easily replaced, unlike skin wings of bats/pterosaurs

Major Orders of Birds, Include

Passeriformes, Apodiformes, Piciformes, Psittaciformes, Charadriiformes, Columbiformes

Major Orders of Birds (continued), Include

Falconiformes, Galliformes, Gruiformes, Anseriformes, Strigiformes, Ciconiiformes, Procellariiformes, Sphenisciformes, Dinornithiformes, Struthioniformes

Feathers, Developed from reptile scales

linked structures provide continuous surface with sturdy but flexible shape

Archaeopteryx, First known bird

had skull with teeth, long reptilian tail, feathers on wings/tail; forelimbs like theropods; feathers probably evolved for insulation

Adaptations for flight in birds, Include

feathers, hollow bones, physiological mechanisms for flight

Modern Birds, Diverse but share characteristics

beaks and feet provide info about habits/food; examples include owls (curved talons), ducks (flat beaks), finches (short thick beaks)

Bird Physiology, Efficient respiration

air passes all the way through lungs in single direction

Bird Physiology, Efficient circulation

4-chambered heart, rapid heartbeat; endothermy (40-42°C) permits higher metabolic rate

Class Mammalia, About 5,000 species

lowest number among vertebrate classes; almost 4,000 species are rodents, bats, shrews, or moles

2 fundamentally mammalian traits, Hair

long keratin-rich filaments for insulation, camouflage, sensory structure

2 fundamentally mammalian traits, Mammary glands

females secrete milk to nourish young

Other Notable Features of Mammals, Endothermy depends on higher metabolic rate

4-chambered heart, respiration using diaphragm; placenta in most mammals

Mammalian Features, Digestion of plants

herbivorous mammals rely on bacteria for cellulose breakdown

Mammalian Features, Development of hooves/horns

hooves are specialized keratin pads; horns are bone surrounded by keratin; antlers are bone only

Mammalian Features, Flying mammals: Bats

only mammals capable of powered flight; wing is leathery membrane over finger bones; navigate by echolocation

History of Mammals, Mammals have existed since ~220 MYA

tiny, shrewlike, insect-eating, tree-dwelling; reached maximum diversity late in Tertiary (~15 MYA)

Monotremes, Lay shelled eggs

only three living species: duck-billed platypus and 2 echidna species

Marsupials, Major difference is pattern of embryonic development

short-lived placenta; young crawl into pouch and continue development; kangaroo (Australia), opossum (North America)

Placental Mammals, Produce true placenta nourishing embryo throughout development

forms from fetal and maternal tissues; includes most living mammals

Major Orders of Placental Mammals, Include

Rodentia, Chiroptera, Eulipotyphla, Primates, Artiodactyla, Carnivora, Lagomorpha, Cetacea, Edentata, Perissodactyla, Proboscidea

Evolution of Primates, Primates gave rise to humans

evolved two features for arboreal success: grasping fingers/toes (opposable thumb) and binocular vision

Living Primates: Anthropoids, Include monkeys, apes, humans

almost all diurnal with color vision; expanded brain; complex social interactions; extended care for young

Hominoids, Include

apes (gibbon, orangutan, gorilla, chimpanzee) and hominids (humans)

Apes versus Hominids, Common ancestor was arboreal climber

hominids became bipedal (walking upright); apes evolved knuckle-walking

Apes versus Hominids, Differences related to bipedal locomotion

human vertebral column more curved; spinal cord exits from bottom of skull; weight carried on lower limbs

Australopithecus, Includes 7 species

older and smaller-brained; hallmark is bipedalism

Bipedalism, Evolved as australopithecines left forests for grasslands

fossils show bipedalism 4 MYA; brain expansion not until ~2 MYA; reasons for evolution still controversial

Genus Homo, First humans evolved from australopithecine ancestors about 2 MYA

thought to be from Australopithecus afarensis; Homo habilis had larger brain (680 cm³ vs 400-550)

Homo erectus, Larger than Homo habilis

1.5 m tall, 1000 cm³ brain; widespread in Africa, migrated to Asia/Europe; lived in tribes of 20-50 in caves

Homo floresiensis, Discovered in Indonesia 2004

lived 60-100,000 years ago; diminutive stature; coexisted with miniature elephant; more closely related to H. erectus than H. sapiens

H. floresiensis, Small size may be example of

island dwarfism

Modern Humans, First appeared in Africa >500,000 years ago

three species thought to have evolved: H. heidelbergensis, H. neanderthalensis, H. sapiens (some lump all three)

Neanderthals, Homo neanderthalensis

made diverse tools, cared for sick, buried dead; first evidence of symbolic thinking; disappeared ~34,000 years ago; up to 4% DNA in some modern humans

Homo sapiens, Only surviving hominid

progressive increase in brain size; effective tool use; refined conceptual thought; symbolic language; extensive cultural experience

Human Races, Humans differentiated in traits as spread worldwide

all capable of mating producing fertile offspring; relied on visual cues (skin color) to define races; constant gene flow prevented subspecies formatio