Chordates

NonVertebrate Chordates, Fish, Amphibians, Reptiles and Mammals

General Chordate Characteristics• At some stage of development, all

vertebrates share the four features:1. Notochord-long supportive rod that

runs through the body, most only have it while embryos

2. Dorsal hollow nerve cord-nerves branch from this cord and connects to internal organs, muscles and sense organs

3. Pharyngeal gill slits-paired structures in the throat region, in some develop gills

4. Tails-can contain bone and muscle, used for swimming in some adult species.

• hollow nerve cord

• tail

• notochord

• pharyngeal slits

Endoskeleton

• Internal skeleton• Made of either bone or cartilage• Grows with the body, allows vertebrates to

grow to large sizes• Most have a strong supporting structure

known as the vertebral column, or backbone• The vertebrae enclose and protect the spinal

cord.

Control of Body Temperature

• Endotherms- use metabolic heat to keep tissues warm– Live in a wider range of

climates than ectotherms.

• Ectotherms-regulate body temperature by surrounding envrionment.

Development

• Bilateral symmetry• Deuterostome• Coelomate

Nonvertebrate Chordates

• Tunicates-closest relatives to vertebrates– Filter feeders, mobile

larvae, sessile adults

• Lancelets- small fishlike creature that is mobile from larval to adult form-keep all four structures

from birth through adulthood

Jawless Fish, Agnatha• Body temp regulation: Ectothermic

(all fish exist in homeostasis at the same temperature as their surroundings)

• Skin/body: skin covering the body, no scales, no fins or limbs, no jaws, eel-like body with compressed caudal fin.

• Skeleton: cartilaginous endoskeleton

• Feeding: carnivores, parasites and scavengers

• Respiration: gills • Circulation: open circulatory system

Gills are shown above

• Excretion: ammonia waste released through the gills into the surrounding water– Solid waste is excreted through

cloaca (a orifice that combines the urinary, digestive, and reproductive tracts)

• Reproduction: hermaphroditic, external fertilization

• Sense organs: lateral line that is used to detect movements and vibrations in surroundings

• Examples: hagfish and lampreys

Cartilaginous Fish, Chondroicthyes• Body temp. regulation: Ectothermic• Skin/body: Denticles (tooth-like

scales covering the skin), paired fins, mouth with several rows of triangular teeth, large caudal fin

• Skeleton: cartilaginous endoskeleton.

• Feeding: carnivores (predators) and filter feeders.

• respiration: gills• Circulation: Closed system, 2-

chambered heart pumps blood around the body in a single loop system.

• Excretion: kidneys filter wastes from blood and conserve water loss during excretion• Solid waste is expelled

through cloaca.

• Reproduction:are Viviparous (embryos stay in the mother’s body after internal fertilization and young are born alive)

• Sense organs: lateral line• Examples- Sharks and rays

Bony Fish, Osteoicthyes• Body temp regulation: Ectothermic• Body/Skin: broad flat scales and

skin that secretes mucous to reduce friction while fish swim, paired fins made of rays/spines (ray fins) and fins with out rays/spines (lobed fin)

• Skeleton: bone.• Feeding: as predators, scavengers,

detrivores, and filter feeders.• Respiration: gills (have an

operculum to regulate water over gills)

• Circulation: 2 chambered heart, (1 way circulation) countercurrent flow of the movement of water against the flow of blood in the fish’s gills.

• Excretion: kidneys filter wastes and prevent water loss during excretion• Solid waste is expelled through

cloaca.• Reproduction: species determine

internal/external fertilization, most are oviparous (external fertilization) (eggs hatch outside the mother’s body) some are ovoviviparous(eggs stay in mother’s body after internal fertilization, develop inside egg and are born alive)

• Sense organs: lateral line system

• Presence of swim bladder to help maintain buoyancy

• Transitional species: lobed fin fish thought to be the precursor to amphibians.

• Examples: Guppies, Salmon, angelfish, goldfish, perch

Amphibians• Body temp regulation: Ecothermic• Skin/body: They have smooth

moist skin. Internal skeleton is made of bone. (large shoulders and hip bones allowed movement from water to land)

• Tympanic membrane-detect sound vibrations (copy down on your sheet!)

• Feeding: Carnivores and insectivores

• Respiration: larva diffusion through skin and gills, adults poorly developed lungs also rely on skin

Amphibians• Circulation: 3 chambered heart

that is composed of 2 atria and 1 ventricle, double loop system

• Excretion: Kidneys filter liquid waste and it is released from the bladder, solid waste is removed through the cloaca .

• Reproduction: is mainly external, with the exception of caecilians which is internal– Must release eggs (through cloaca)

in a moist environment (some lay directly in water, other moist ground, or in sacs on the female’s back

• Amphibians start life cycle under water and move to land at adult hood. (Double life) – May go through

metamorphosis

• Examples: toads, frogs, salamanders and caecilians

Reptiles• Body temp regulation:

Ecothermic• Skin/body: Dry scales, toes

with claws, body plan better adapted to living on land

• Skeleton: bone• Feeding: Carnivores and

herbivores.• Respiration: Lungs are

spongy, allows for more gas exchange. Most reptiles have 2, snakes only have 1 lung.

• Circulatory: Have a double loop. Non Crocodilian have a 3 chambered heart. Crocodilian reptiles have a 4 chambered heart.

• Excretion: Kidneys, bladder and cloaca are used to eliminate waste.

• Reproduction: Fertilization is internal and first animals to use an amniotic egg for offspring, may have oviparous birth (eggs deposited into an external nest) or viviparous (reptile retains egg and gives birth to live offspring)

Amniotic Egg

• Amniotic eggs have a tough shell that is almost completely waterproof, and contains all the developing embryo needs until it is ready to break free from shell.

Reptiles

• Examples include: Snakes, lizards, turtles, alligators, and crocodiles

Aves• Body Temp Regulation:

Endothermic• Body/Skin: Feathers and dry

scales cover the body, horned beak, no teeth, rearranged muscle in hips and legs, forelimbs are wings

• Skeleton: hollow bone, fused collarbones that form v-shape wishbone

• Feeding: Carnivores, Insectivores, Herbivores, Nectivores

• Respiration: Lungs with air sacs, allows for more efficient oxygen exchange with unidirectional flow.

Aves• Circulation: Have a 4

chambered heart composed of 2 atria and 2 ventricles.

• Excretion: Kidneys and cloaca are used to eliminate waste. Birds do not urinate (with the exception of the ostrich).

• Reproduction: Fertilization is internal and use an amniotic egg with a hard shell for offspring, Have oviparous birth (eggs deposited into an external nest).

Aves

• Examples include: extinct archeopteryx, hummingbird, green woodpecker, blue-footed booby, bald eagle

green woodpecker

blue-footed booby

Bald eagle

Mammals• Body temp regulation:

Endothermic• Skin/body: Hair covers

the body, have middle ear bones to detect sound

• Skeleton: made of bone• Feeding: Carnivores,

Omnivores, and Herbivores

• Respiration: Lungs are spongy, allows for more gas exchange. All mammals have 2

Mammals• Circulatory system: Have a 4

chambered heart composed of 2 atria and 2 ventricles.

• Excretion: Kidneys, bladder, anus and sweat glands (not all mammals) are used to eliminate waste.

• Reproduction: Fertilization is internal. However, mammals are classified differently depending on how they give birth.

• Most have sweat (used also to eliminate heat) and sebaceous (fat secreting) glands

• Produce milk to nourish young, using mammary glands

Placental Mammals

• All bear live young, which are nourished by placenta (a specialized embryonic organ attached to the uterus wall) before birth in the mother's uterus

Placental Mammals

• Examples include:– Humans– Dolphins– Field mice– Badgers

Marsupial Mammals

• No placenta.• After 4-5 wks., young

emerge from the birth canal in an extremely undeveloped state.

• Immediately after birth, the tiny offspring, crawls along its mother’s body and finishes developing attached to a nipple located inside the mother’s pouch.

Marsupial Mammals

• Examples include:– Koalas– Kangaroos– Sugar gliders– Opossums

Monotreme Mammals• Mammals with

reptilian-like features including a cloaca.

• These mammals lay reptile-like eggs.

• After the babies hatch, the mothers nourish their young with milk.

Monotreme Mammals

• Examples include:– Duck-billed platypus– Echidna