BIO 202 Chordates 2 - Exam 4

living endoskeleton of subphylum vertebrata

grows with body; cartilage then bone

pharynx of subphylum vertebrata

increased respiratory function; supported high metabolic rates

nervous system of subphylum vertebrata

evolution of complexity; neural crest, greater development of brain, skull, and sensory organs

paired appendages of subphylum vertebrata

pectoral and pelvic girdles and limbs; originated for balance and swimming

jaws of subphylum vertebrata

modified gill arches and cranium

when did vertebrates invade land

Devonian period (about 400 mya)

adaptations for land

limbs and lungs

limb adaptations

from lobe-fins for support; air has less buoyant density than water

lung adaptations

in addition with cutaneous respiration; oxygen content higher in air than water

what do lungs do

prevent desiccation (drying out) and temperature regulation

class amphibia

4 limbs, bony skeleton; lungs with internal nostrils; metamorphosis of aquatic larvae to terrestrial adult; larvae and some adults have lateral-line system; ectothermic

how do amphibians respirate

across skin; desiccate easily

ectothermic

low metabolic rate

two specific characteristics of amphibians

brain and 3 chambered heart

brain development

forebrain- olfaction, midbrain- vision, hindbrain- hearing, balance

3 chambered heart

2 atria, 1 ventricle; mixed circulation (oxygenated blood returns to heart); skin has lots of blood vessels

difference of eyes between fish and amphibians

fish have flat eyes; have to have flat eyes to interpret information in water

orders of class amphibia

gymnophiona, urodela, anura

order gymnophiona

ex: caecilians; elongated, limbless amphibian with dermal scales, adults blind; burrowing or aquatic; predators

order urodela

ex: salamanders; mostly in temperate regions, most limbs of similar size and set at right angle, larvae and adults carnivorous

order anura

ex: frogs and toads; aquatic and terrestrial species; no tail in adults, present in larvae; legs modified for jumping; protrusible , sticky tongue; hibernation in temperate zones; carnivores, teeth for grasping; herbivores as larvae

anuran life-cycles

external fertilization by amplexus (no copulation); slow metamorphosis; tail, gills reabsorbed; legs, lungs develop

tissue type of amphibians

triploblastic

symmetry of amphibians

bilateral

protostome/deuterostome of amphibians

deuterostome

circulation of amphibians

closed

excretion of amphibians

kidneys

reproduction of amphibians

sexual (oviparous, mostly)

distinguishing characteristics of amphibians

amphibious life history, strange blood circulation

clade amniota

includes reptiles with birds and mammals; presence of amnion, a separate membrane; thicker keratinized skin

4 membranes

ammion, chorion, two shell membrane (yolk sac and allantois)

amnion

protects embryo in the amniotic cavity

yolk sac

encloses a reserve of nutrients; gets smaller with age

allantois

contains wastes from embryo; gets bigger with age

chorion

together with allantois, allows gas exchange

non avian reptiles

similar to amphibians; 3 chamber heart allows lung bypass

crocodilians, birds, mammals

4 chamber heart, no mixing, high pressure; double circulation

orders of non-avian reptiles

testudines, squamata, crocodilia

order testudines

ex: turtles; carapace + plastron = shell; omnivorous

temperature affects what in order testudines

affects sex ratio; cold - male, warm - female

order squamata

ex: lizards and snakes; 2 subgroups (sauria and serpentes); copulation with hemipenes; mostly oviparous, some viviparous

suborder serpentes

snakes; all carnivorous; one lung, kidneys stacked; lack eyelids and external ears; venom in fangs

order crocodilia

crocodiles; share ancestry with dinos and birds; all predators; single penis; temperature-dependent sex determination; females guard nest and young for up to 2 years