Biology Ch26 - (Amniotes)

Amniotes examples

Reptiles, birds, and mammals

Amniotie embryos

Develop in fluid-filled sacs

Amniotes can be

Ectothermic or endothermic

Reptiles, birds, and mammals characteristics

Presence of an amnion

Birds characteristics

Presence of feathers and air sacs

Mammals characteristics

Presence of hair and mammary glands

Importance of the development of the amniotic egg

Allowed vertebrates to reproduce on land,

without the need of an egg to develop in water

Chorion

Allows gas exchange with outside environment

Amnion

Protects and surrounds the embryo

Yolk sac

Contains the nutrient supply for the growing embryo

Allantois

Holds waste materials as the embryo grows

Pulmonary circuit

Moves blood from the heart to the lungs

Systemic circuit

Moves blood from the heart to the rest of the body

Heart of an amniote

Either three or four chambered heart

Birds and mammals’ heart

Four chambered heart

Ectotherms

Body temperature is dependent on the surrounding environment

Endotherms

Use metabolic heart to keep tissues warm

Reptiles’ characteristics

Ectotherms, covered in dry scales,

reproduce by laying or retaining amniotic eggs,

three chambered heart except for the crocodile (4 chambers)

Cloaca (klaueika)

It is a chamber that receives the digestive waste

Oviparous

Reptiles deposit eggs into an external nest

Viviparous

Reptiles retain eggs and give birth to live offspring

Three groups of Amniotes

Synapsids, anapsids, diapsids

Number of holes in anapsids’ skull

0

Number of holes in synapsids’ skull

1

Number of holes in diapsid’s skull

2

Example of anapsid

Turtles

Examples of synapsids

Mammals

Types of diapsids

Birds, lizards, crocodilians

Four modern groups of reptiles

Turtles, sphenodons, snakes and lizards, crocodilians and alligators

Turtle characteristics

Bony shell that encases the body, anapsids

Sphenodons characteristics

Closely related to lizards (scaly reptile),

primitive characteristics, diapsids

Snakes and lizards characteristics

Diapsids,

shed skin at regular intervals,

flexible skull, Jacobson’s organ (pull out tongues to pick up odors and detect prey)

Crocodilians and alligators characteristics

Diapsids, semi-aquatic predators, 23 species

Birds’ body temperature

41 degrees, endotherms

Birds characteristics/features

Hollow bones,

fused collarbones that form a v-shaped wishbone,

rearranged muscles in the hips and legs, and feathers

Birds’ characteristics for flight

Strong flight muscles to move the wings,

active metabolism that provides energy to the muscles,

hollow bone structure to minimize weight

Extra air sacs to meet oxygen demand

Webbed feet on birds

Helps with swimming

Heavy claws on birds

Used to kill prey

Different toe location on birds

Helps hold onto the wood parts on trees

Mammal anatomical characteristics

Hair to retain heat,

Mammary glands to produce milk,

Middle ear containing three bones, jaw let’s them chew food

Only organ that mammal’s have that other animals don’t

Diaphragm

Adaptations in the mammalian jaw

Secondary palate roof of the mouth closed off air passage (so you can breath and eat at the same time),

Muscles move jaw side to side

Monotremes

Mammals that reproduce by laying eggs (duck-billed platypus and echidnas)

Placental mammals (Eutherians)

Give birth to live young that completed fetal development in the uterus (most familiar mammals and humans)

Marsupials

Give birth to live young that grow to maturity inside a pouch (koala and kangaroo)