zoology exam 6

what are three types of fenestra patterns present in amniotes, provide an example of each?

anapsid- turtles, synapsid- mammals, and diapsid- most modern reptiles

why was the amniotic egg a major factor in the success of tetrapods on land?

it allowed them to break their dependence on aquatic environments for reproduction

why aren’t reptile scales homologous with fish scales?

they come from different embryonic tissues

compare and contrast respiration between frogs and lizards

frogs have a dual mode system using moist, porous skin and their simple lungs with positive pressure swallowing, often while they are particularly submerged. lizards rely completely on a more advanced negative pressure thoracic breathing using their ribs to draw the air into their lungs allowing higher activity. they are the same by both being ectothermic, requiring lower oxygen levels than warm blooded animals, and they both breathe air.

what are the four living orders of non-avian reptiles? Know the actual name of the order, what organisms belong to that order, and a defining characteristic of each.

order squamata ( scaled reptiles)- lizards, snakes, and worm lizards, they possess a flexible, kinetic skull with a moveable quadrate bone, allowing them to open their jaws extremely wide to swallow large prey whole.

Order testudines ( chelonia) - turtles and tortoises, they have a bony or leathery shell consisting of a dorsal carapace and a ventral plastron, which is fused to their vertebrae and ribs

order crocodilia ( crocodilian)- crocodiles, alligators, caimans, and gharials, they are the only living reptile with a four chambered heart and thecodont dentition where teeth are set in sockets for a powerful bite

order sphenodontia ( rhynchocephalia) - tuataras, they have a well developed parietal eye located under the skin on top of the head which includes a retina and lens to sense light

what is temperature dependent sex determination, and what groups of reptiles exhibit this trait?

it is a biological process where the sex of an offspring is determined by the ambient temperature experienced during a critical period of embryonic development rather than by sex. crocodiles, most turtles, tuataras, some lizards, and snakes

what is a kinetic skull and what organisms have this?

this is a skull where the joints between various parts are significantly mobile, rather than being fused into a solid unit. squamates(snakes and lizards), brids, and most fish

what are three differences between lizards and snakes? (ps. differences in one trait does not equal two differences. for example lizards have external ear openings and snakes lacking external ear openings is a difference in ear structure, just one difference not two)

eyelids and blinking- most lizards have moveable eyelids that allow them to blink and close their eyes. snakes lack eyelids entirely instead they have a clear protective scale called a spectacle or eye cap that covers their eye

external ear openings- lizards have external ear openings, snakes do not have external ear openings

belly scales and movement- snakes possess specialized, wide belly scales and powerful muscles that allow them to grip the ground and move in a fluid motion, lizards including legless ones generally have uniform scales all around their bodies and they lack specialized belly scutes, which makes them more stiff side to side jerking movement

what is the function of a Jacobson’s organ and why is this significant for snakes?

it is to process non-volatile chemical cues, essentially allowing the animal to “smell” its environment with extreme precision. it is significant for snakes is by its tongue organ link- snakes use its tongue to collect chemical particles from the air and ground and when the tongue retracts it fits into two pits in the roof of the mouth delivering those particles directly to the jacobson’s organ, the directional tracking- because of its forked tongue it can pick up different concentrations of the chemicals on each tip the jacobson’s organ then processess this data to tell the snake which direction a scent is coming from, and the survival essentials- is a snakes primary tool for hunting, mating, and avoiding predators, making it critical to their survival than their relatively poor eyesight or hearing.

what are two families of venomous snakes and what is the difference between their fangs?

family elapidae- they have short fixed fangs located at the front of their upper jaw

family viperidae- they have long hinged fangs that fold up against the roof of the mouth when it is closed

how do zoologists know that Archaeopteryx is a link between modern birds and extinct theropod dinosaurs?

because its anatomy is a unique blend of reptilian features typical of theropod dinosaurs and avian features characteristics of modern birds

what are the two extant groups of birds, what is a defining characteristic of each and provide an example of each

palaeognathae (ancient jaws)- they have a primitive, rigid palate structure. most members are ratites and they lack a keeled sternum. ex. ostritch

neognathae( new jaws)- have a highly flexible palate with mobile joints which allows for a more diverse beak movements and specialized feeding. ex. sparrow

why are feathers homologous with reptile scales?

because they share a common evolutionary origin which develops from the same ancestral embryonic structures and genetic pathways

what are three specializations of bird skeletons that aid in flight?

hollow bones, keeled sternum, and extensive bone fusion

compare and contrast respiration between birds and lizards

lizards- have to hold their breath while running because the same muscles are used for both movement and breathing.

birds- can breathe and fly simultaneously. it takes two full breaths for a single pocket of air to move through the entire bird system, ensuring that the lungs are recieving fresh oxygen

both of the groups lack a muscular diaphraghm and they rely on moving their ribcage or body wall to ventilate

name and define three theories for the origin of bird flight

the arboreal (trees-down) theory- flight began with tree dwelling ancestors that leaped between branches. feathers evolved to aid in gliding with then transitioned into powered flapping to extend travel distance or to improve landings.

the cursorial (ground-up) theory- flight evolved in small ground running predators. animals used their feathered forelimbs for balance and stability while running at high speeds to provide extra lift to jump higher and catch insects to avoid predators

wing assisted incline running- flight evolved from birds using their wings to generate downforce, which allows them to run up steep or verticle surfaces to escape danger

what are advantages of flocking?

protection from predators, enhanced foraging, aerodynamic efficiency, and social and reproductive benefits

name and describe the four forms of bird wings and provide an example for each

elliptical wings- short, broad, and rounded wings with a low aspect ratio designed for maneuverability and quick takeoffs in cluttered environments which allows birds to navigate through dense vegetation and make sharp turns

high speed wings- relatively small, narrow wings that taper to a point. these wings have a high aspect ratio and are often swept back to minimize drag to allow for rapid sustained flight or high speed

active (dynamic) soaring wings- very long, narrow, pointed wings with no slots at the tips they are built for gliding over oceans, using the dynamic soaring technique to harvest energy from wild gradients above waves with minimal flapping

passive ( high-lift) soaring wings- broad wings with “fingered” primary feathers at the tips the slots help reduce turbulence and increase lift at slow-speeds which allows birds to soar on thermal updrafts while carrying heavy loads.

describe bird mating systems, what are the types of polygany?

how birds pair up to reproduce and raise their youngs.

resource-defense polygyny, female defense polygyny, and lek polygyny

what are four reasons that bird populations are declining globally?

agricultural expansion and intensification, logging and deforestation, invasive species, and climate change

describe the origin and early evolution of mammals. what groups were important, what was gained or lost with each?

a story of gradual transition from a reptile like body plan to a high metabolism mammalian one. this process took over 150 million years beginning with the synapsids.

pelycosaurs ( early synapsids)- gained- the synapsid skull which provided more space for jaw muscle attachment. lost- the primative anapsid skull of their ancestors

therapsids ( advanced mammal like reptiles) - gained- an upright gait and heterodont dentition. lost- the sprawling lizard like posture

cynodonts ( dog teeth) - gained- a secondary palate, turbinate bones in the nose, and potentially hair and endothermy. lost- the heavy reptilian jaw structure

what are three types of hair adaptions (specializations)?

whiskers, quills or spines, and underfur

what is the difference between horns and antlers? provide an example for each

antlers- entirely solid bone covered in a highly vascular skin called velvet which is rubbed off once the bone hardens. they are shed and regrown every year typically branched. ex- white tailed deer

horns- bony core covered by a permanent keratin sheath they are permanant and grow continuosly throughout the animals life ex-domestic cow

how are mammals capable of exploiting a wide variety of food sources?

they have heterodont dentition ( specialized teeth), specialized digestive systems, the secondary palate, and a high metabolic rate

name and describe the four general trophic categories of mammals, provide an example for each. how is dentition different in each group?

insectivores- these mammals eat primarily insects and other small invertebrates. they have numerous sharp, pointed teeth designed for piercing and crushing the hard exoskeletons of insects. ex- shrews

carnivores- feed primarily on the flesh of other vertebrates. they have large prominant canines for piercing and holding prey. ex- lions

herbivores- feed on plant matter. have well developed incisors for nipping vegetation and broad, flat molars with complex ridges for grinding tough cellulose. ex-horses

omnivores- eat both plant and animal matter. have versatile, unspecialized teeth, sharp incisors for biting and molars for crushing varied food. ex- humans

how is the digestive system different between ruminants, cecotrophs, and carnivores?

ruminants- have a four chambered stomach, the first and largest chamber called the rumen acts as a fermentation vat where bacteria breaks down cellulose before food reaches the true stomach

cecotrophs- have a simple stomach but a massive enlarged cecum, fermentation happens after the food has passed through the stomach and small intestine.

carnivores- have a short simple digestive tract meat is highly digestible and nutrient dense so it does not require complex fermentation

what are three extant groups of mammals, describe reproduction for each and provide an example for each

monotremes (egg laying mammals) - the only mammals that lay leathery eggs rather than giving birth to live young unlike other mammals they provide milk but they lack nipples so the milk is secreted onto patches of skin for the young to lap up. ex- platypus

marsupials ( pouched mammals)- they give birth to undeveloped embryonic young after a very short gestation period then the tiny offspring crawls into a marsupium, attaches to a nipple, and completes its development while nursing. ex- kangaroo

eutherians ( placental mammals)- have a complex placenta that connects the fetus to the mothers uterus which provides a highly efficient exchange of nutrients and oxygen. this allows for a long gestation period which results in young that are much more developed at birth compared to marisupials. ex- humans

what is torpor and how does it differ between large mammals and small mammals?

a state of decreased physiological activity characterized by a controlled reduction in metabolic rate, heart rate, and body temperature.

small mammals- frequently use daily torpor, short spurts typically lasting a few hours to less than 24 hours, extreme drops body temp can fall as low as -38 degrees celcius to below freezing, metabolic rate can drop low as 5-30% of their basal metabolic rate, slow and energy intensive may involve violent shaking and muscle contractions, and often appear completely motionless

large mammals- light hibernators or seasonal torpor users, prolonged periods that can last for days or weeks throughout winter, moderate drops they maintain near normal body temp, metabolism slows but remains high enough for relatively quick arousal, can wake up fairly easily and quickly if disturbed, and remain somewhat responsive to external sounds.

what are the defining characteristics of new world monkeys, old world monkeys, and apes? provide an example for each

new world monkeys- tail: many have a prehensile tail that acts like a fifth limb for grasping branches, nose: they have flat noses with side opening nostrils, habitat: strictly arboreal. ex- spider monkey

old world monkeys- tail: they have tails but they are never prehensile, nose: they have narrow noses and downward pointing nostrils, anatomy: many have ischial callosites and some have cheek pouches for storing food, habitat: found in Africa and Asia includes both arboreal and ground dwelling species. ex- baboons

apes- tail: they lack a tail entirely, anatomy: they have a larger brain to body size ratio than monkeys and more flexible shoulder joints allowing swinging through trees, posture: generally more upright includes the great apes and lesser apes. ex- chimpanzee

what traits were evident in ardipithecus ramidus and australopithecus afarensis that help us understand the evolution of humans?

ardipithecus ramidus- bipedalism and climbing, reduced canines, brain size.

australopithecus afarensis- obligate bipedalism, laetoli footprints, upper body, and intermediate dentition.