VERTEBRATES

JAWLESS FISH

• Vertebrates were characterised by an array of jawless fishes.
• Small cartilage,Marine, near ocean floor, Feed in worms
• Attack dead and dying fish, Fresh and salt water
• The ones not extint today are : hagfishes and lampreys
• They represent the early branches of the chordate evolutionary tree.

Hagfish

• Stiff by a notochord
• Skeleton is made my small cartilage elements
• Most systematics do not consider them to be vertebrates
• They represent the chordate group that is most closely related to the vertebrates.
• Exclusive marine. Burrowing in the mud of the ocean floor

HAGFISH

• Regarded with great disgust by some fishermen
• "Slime balls of the sea"
• Avidly pursue by commercial fishermen
• Fun fact: most leather items are made from tanned hagfish

Lampreys

• Nerve chord is protected by segments of cartilage
• Considered true vertebrates
• Both fresh and salt water
• Must return to fresh water to spawn
• Some are parasitic

LAMPREYS

• In the absence of effective predators, they multiply prodigiously
• Fun fact: in the 1920's, lampreys spread into the Great Lakes.

CARTILAGINOUS FISHES

• 625 marine species
• Predators that lack any bone
• Protected by a leathery skin
• Respire using gills
• Two-chambered hearts

CARTILAGINOUS FISHES

• Some must swim to circulate water
• Some are very large
• Example: whale shark

RAY-FINNED FISHES

• Most vertebrate diversity
• 24,000 species
• Every watery habitat
• Fins: formed by webs of skin
• Skeletones made of bones

RAY-FINNED FISHES

• Skin is covered with interlocking scales
• Swim bladder, evolved from lungs
• Variety of different forms and lifestyles
• Extremely important source of food for humans
• Float effortlessly

AMPHIBIANS

• 4,800 species
• Aquatic and terrestrial existence
• Three-chambered heart
• Lungs are poorly developed
• Respiratory organ requires skim to remain moist.

AMPHIBIANS

• Tied to moist habitats
• Fertilization is external
• Most species keep their eggs under water
• Amphibians go through a metamorphosis
• Vulnerable to pollitants and to environmental degradation

REPTILES

• Evolved from an amphibian ancestor
• Some are completely independent of their aquatic origins
• Evolved a scaly skim that resists water loss
• Evolved internal fertilization
• Evovled a shelled amniote egg

REPTILES

• More efficient lungs than earlier vertebrates
• Do NOT use skin as respiratory organ
• Three-chambered heart
• Evolved features to provide better support
• Effiecent movement in land

BIRDS

• 9,600 species
• Subset of an evolutionary group including birds and reptiles
• Retain scales on their legs
• Anatomy and physiology adapt to help them to fly
• Light for their size

BIRDS

• Bones have been lost in evolution
• Reproductive organs shrink during non breeding periods
• Female periods possess a single ovary
• Maintain body temperature high
• High metabolic rate

BIRDS

• Warm-blooded animals
• Must eat frequently
• Circulatory and respiratory adaptions
• Four-chambered heart
• Respiratory system is supplemented by air sacs

MAMMALS

• Milk-producing mammary glands
• Mammalian nervous system
• Brain highly developed
• Long periods of parental care after birth
• Alter behaviour on the basis of experience

MONOTREMES

• Lay eggs instead of giving birth
• Three species: platypus and two echidnas
• INcubated by mother for 10-12 days
• Lack of nipples
• Milk goes out through ducts on the mom's abdomen

MARSUPIAL

• Embryos develop in the uterus
• Born at a very immature stage of development
• Post birth development sometimes happens in a protective pouch

PLACENTAL

• Placentas are more complex
• Retain their young uterus longer
• Offspring's development ins complete before birth
• Diversity of form
• Fun fact: largest group: bats and rodents.