Echinoderms and Tetrapods

These flashcards cover basic terms and definitions relevant to the study of Echinoderms and Tetrapods.

Echinodermata

A phylum of marine animals that includes starfish, sea urchins, and sand dollars, characterized by a calciferous endoskeleton and water vascular system.

Tetrapods

A group of animals that include amphibians, reptiles, birds, and mammals; they have four limbs and are adapted to life on land.

Amphibians

A class of tetrapods that includes frogs, salamanders, and caecilians, characterized by a life cycle that includes both aquatic and terrestrial stages.

Amniotic Egg

An egg that contains an amnion, allowing the embryo to develop in a terrestrial environment, found in reptiles, birds, and mammals.

Viviparity

The reproductive strategy in which animals give birth to live young rather than laying eggs.

Poikilothermy

The ability of an organism to have a variable body temperature that fluctuates with the environment.

Homeothermy

The ability of an organism to maintain a stable internal body temperature regardless of external conditions.

Counter-current heat exchange

A mechanism that helps to retain body heat by allowing warm arterial blood to heat cool venous blood.

Metamorphosis

A developmental process through which animals, especially amphibians, undergo a significant change in form and function, typically from larval to adult stages.

Amniotes

A clade that includes all tetrapods except amphibians, characterized by the presence of an amniotic egg.

What are mammals known for?

Mammals are warm-blooded vertebrates with hair or fur and mammary glands that produce milk for their young.

What is thermoregulation?

Thermoregulation is the process by which an organism maintains its internal temperature within a tolerable range.

What are the main ways mammals thermoregulate?

Mammals thermoregulate through behaviors, physiological adaptations like shivering, sweating, and altering blood flow, and insulative structures like fur.

What are reptiles?

Reptiles are cold-blooded vertebrates that have scales and lay eggs, typically requiring external heat sources for metabolic processes.

What is Allen's Rule?

Allen's Rule states that endothermic animals in colder climates tend to have shorter appendages (like limbs and ears) compared to those in warmer climates.

What is Bergmann's Rule?

Bergmann's Rule states that within a species, individuals in colder climates tend to be larger than those in warmer climates to conserve body heat.

What is temporal heterothermy?

Temporal heterothermy refers to organisms that can vary their body temperature at different times, such as during day and night. (ex. torpor → hibernation)

What is regional heterothermy?

Regional heterothermy is when different parts of the body of an organism maintain different temperatures.

What is ectothermy?

Ectothermy is the biological trait of relying primarily on external environmental heat sources to regulate body temperature.

What is endothermy?

Endothermy is the ability of an organism to generate and maintain its own body temperature through metabolic activity.

What is vasoconstriction?

Vasoconstriction is the narrowing of blood vessels, which decreases blood flow and raises blood pressure, often occurs in response to cold to conserve heat.

What is vasodilation?

Vasodilation is the widening of blood vessels, which increases blood flow and lowers blood pressure, often occurs in response to heat to release excess body heat.

How does vasoconstriction help in thermoregulation?

Vasoconstriction helps in thermoregulation by reducing blood flow to the skin, minimizing heat loss in cold environments.

How does vasodilation aid in thermoregulation?

Vasodilation aids in thermoregulation by increasing blood flow to the skin, promoting heat loss in hot conditions.

What are amphibians?

Amphibians are a class of ectothermic vertebrates that include frogs, salamanders, and caecilians.

Complete Metamorphisis - amphibians

Complete metamorphosis in amphibians involves distinct life stages: egg, larva (tadpole), and adult

Decline of Amphibia

rapid decline because of chytrid fungus, habitat loss, climate change, and pollution

Gas Exchange - Amphibia

through their skin, lungs, gills, and mouth (tadpoles are water breathers and metamorphize into frogs that breathe air)

waste exchange - amphibia

excrete waste across their skin, urine, and gills and excrete ammonia as a primary waste product, allowing for efficient osmoregulation.

Amniotes

all tetrapods except for amphibia. They are characterized by having an amniotic egg that protects the embryo and allows for reproduction in dry environments.

Mammals and reptiles amniotic egg

reptiles and mammals that lay eggs produce amniotic eggs and lay them outside of water. other mammals don’t lay eggs but have amniotic sacs.

Amphibia Reproduction

Amphibians typically reproduce through external fertilization, lots of eggs, but little protection from parents

Vocalization - Amphibians

use vocalization primarily for social interactions, such as attracting mates or establishing territory.

Semiterrestrial - Amphibian

amphibians live both in aquatic environments (like water for breeding) and on land.

Mammals

Egg-laying monotremes, pouch-bearing marsupials, and placental (eutherians)

Mammary glands

produce milk for offspring

Warm-blooded mammals

are mammals that can regulate their body temperature internally, allowing them to thrive in a variety of environments.

Dependent Variable in the figure is : a) body temperature. b) ambient temperature

a) body temperature

Poikilotherm or Homeotherm?

Poikilotherm - body temp is strongly affected by environmental temp

What organism does the gray, dashed line describe best: poikilotherm or homeotherm?

Homeotherm - its hotter at noon than midday but body temp remains steady all day long.

What is/are the independent variables in this figure?

a) time of day

b) body temp

c) poikilotherm vs homeotherm

d) two of the above

e) all of the above

d) two of the above (time of day and poikilotherm vs homeotherm)

Cost and benefits of homeothermy

Homeothermy provides stable body temperatures, allowing for consistent metabolic functions, but it requires more energy to maintain compared to poikilothermy.

Thermoregulatory Adaptations

Insulation - fat, fur, feathers (reduce heat exchange with environment)

Surface area to volume ratio - shorter appendages and bigger body size reduce heat loss, and vice versa

Counter current heat exchange

Counter current heat exchange

helps retain body heat in efficient manner, in which warm arterial blood warms the cooler venous blood returning to the body.

Will the animal lose or gain heat from the environment?

Lose

Which animal will lose the most heat to the environment

The top one → the veins are closer to surface of skin so more heat goes to environment

How will heat transfer between these blood vessels?

a) red to blue

b) blue to red

c) no net change

d) not enough info to tell

a) red to blue → heat will flow from warm to cool

waste exchange for mammals

trough kidneys and urine - in the form of urea

differentiated teeth

in mammals - different teeth for different fuctions

monotremes

lay eggs, have hair, produce milk, and lack nipples (ex. platypus and echidnas)

marsupials

live young (no eggs), nipples provide milk, placenta provides nutrients in utero, born early→develop in marsupiam/pouch (ex. opposumns, kangaroos, koalas)

eutherian

complete embryonic development attached to placenta

placenta

organ combining maternal and embryonic tissues

After gestation…

embyro emerges from mothers body (ex. 9 months for human)

Advantages of viviparity and placenta?

1. Offspring develop at more constant, favorable temp

2. they are physically protected

3. they are portable → mothers aren’t tied to nest

tradeoffs of placenta and viviparity

placenta is energetically expensive to produce and bearing live young is energetically costly (need enough food!)

Reptiles

lizards & snakes, turtles, crocodiles & alligators, and birds

reptile adaptations for life on land

1. watertight skin make by layer of keratin

2. breathe air through well developed lungs

3. excrete uric acid

4. amniotic eggs

5. ectotherms → bask in sunlight, seek shade, etc to keep body temp regulated

Birds

descended from dinosaurs that had feathers → outgrowths of skin made from keratin, providing insulation and used for display (ENDOTHERMIC)

Reptiles in flight

wings/flight evolved indp in pterosaurs, birds, and bats (tetrapod amniotes)