Zoology Lecture 4 (Birds/mammals/biodiversity)

Larynx

Opens and closes glottis during respiratory cycle and prevents foreign material from entering the lower respiratory tract

Trachea

Conducts air to and from the lungs during respiration

Heart

Four-chambered organ (two atria, two ventricles) that receives oxygenated blood from the lungs and pumps it via the arteries throughout the body

Crop

Stores ingested food to await passage to gizzard; found in seed- and grain-eating species

Proventriculus

Mixes food with peptic enzymes for digestion

Gizzard

Thick-walled, muscular pouch that pulverizes and churns food prior to its passage into the intestine; larger in seed-eating species

Pancreas

Produces digestive enzymes that are released into the small intestine

Intestine

Continued digestion of food particles; transports feces to coprodeum of cloaca via peristalsis

Cloaca

Common chamber for collection of materials from the digestive, excretory, and reproductive systems prior to their discharge from the body; partitioned into a coprodeum, urodeum, and proctodeum as in reptiles

sebaceous gland

Secretes oily compound that coats feathers, preventing moisture absorption

Ureters

Transport uric acid mixture from the kidneys to the cloaca

Kidneys

Paired organs that filter nitrogenous wastes from the blood and produce dry uric acid with little water that is transported to the urodeum of the cloaca, where it mixes with feces as it is released from the body

Auditory tube

Channels sound waves to auditory receptors; similar to the ear canal of humans

Cerebellum

Primarily a reflex center for integration of skeletal muscle movements; responsible for coordination and balance

Optic lobes

Process visual information from the eyes

Cerebrum

Largest portion of the brain; interprets sensory impulses and coordinates voluntary movements

Stomach

Produces hydrochloric acid and pepsinogen, which aid in the chemical breakdown of food

Pyloric sphincter

Muscular band that regulates the flow of chyme from the stomach into the duodenum

Liver

Produces bile, converts glucose to glycogen for storage, detoxifies many constituents of the absorbed digested compounds

Bile duct

Transports bile from the lobes of the liver directly to the duodenum

Duodenum

Receives chyme from the stomach along with bile and digestive enzymes from the liver and the pancreas

Jejunum

Responsible for the majority of nutrient absorption and reabsorption of water

Ileum

Continues process of nutrient absorption and reabsorption of water

Cecum

Large, thin-walled pouch demarcating the beginning of the large intestine; contains anaerobic bacteria responsible for fermentation of cellulose and other plant materials; has a reduced appearance and function in carnivores and omnivores

Descending colon

Responsible for reabsorption of water and electrolytes; transports feces to the rectum via peristalsis

Rectum

Final site of water reabsorption and feces dehydration

Class Aves

-birds

-flight(key adaptation) shapes anatomy, ecology, and behavior

-diurnal

-excellent vision, colors & movement are important cues

Diurnal

out during the day

Feathers (birds)

-unique to birds & all birds have them

-composed of keratin-homologous with reptilian scales

-non-living when fully grown (molt)

-precede flight & birds

Skeletal adaptations (birds)

-pneumatized or honeycombed bones

-light, kinetic diapsid skull (can move jaws independently)

-rigid vertebral column with synsacrum, mobile neck

-keeled sternum & furcula

-bones in forelimb- reduced in number & fused to reduce weight

Synsacrum

fusion of hip bones for flight support

Furcula

fused clavicle for muscle attachment

Sternum

flight muscles attach

Muscles (birds)

-highly adapted for flight

-main muscle mass in legs proximal to body and center of gravity

-flight muscles: pectoralis and supercoracoideus- rope & pully system

Wing structure (birds)

-airfoil

-shape varies based on the type of flight

-aquatic birds have dense bones and waterproofed wings

Airfoil

creates both lift and thrust

Digestive system (birds)

-efficient & rapid

-toothless

-large muscular gizzard in stomach

-cloaca (combined urogenital opening)

Respiratory/circulatory system (birds)

-high metabolic rate (endothermic)

-4 chambered heart to separate blood to lungs & body

-1 way movement of air through respiratory system (9 interconnected air sacs)

-high amount of oxygen in lungs all the time to keep up with metabolism

Endothermic

use physiological control to maintain body temperature

Excretory system (birds)

-adapted for production of shelled amniotic eggs

-main nitrogenous waste: uric acid

-no bladder

-salt glands in marine birds

Senses (birds)

-poor sense of smell and taste

-very keen sense of hearing and acute eyesight

Reproductive system (birds)

-designed to decrease weight

-males scrotal only during mating season

-males lack a penis

-females only left ovary is functional

Polygamy

more than one mate during a breeding season

Monogamy

single mate (90% of bird species)

Seasonal monogamy

most birds only pair during the mating season but may not be faithful

Ratites (Paleognathae)

-emu, ostrich, kiwi

-flightless birds

-no keel on sternum

-poorly developed pectoral muscles

Mammal shared common ancestor

Therodontia (subclass of therapsid reptiles)

-high metabolic rate

-increased jaw musculature

-skeletal changes: upright stance

-secondary bony palate

Hair (mammals)

-definitive: no homologs

- composed of keratin from dermis

-variously modified

Glands (mammals)

1) scent glands: communication (not unique)

2) sweat glands: evaporative cooling

3) sebaceous glands: protects hair

4) mammary glands: used to lactate young

Lactation

-reproduction not tied to seasonal food supply

-store fat and energy in milk to use later

-mom can raise offspring solo

-makes vivipary easier- young born at relatively undeveloped state

Remodeled jaw joint (mammals)

reduction in bones in lower jaw and changes in joints. more rigid/less kinetic. strong, not flexible. more acute hearing sensitivity. bones from reptiles are repurposed to be inner ear in mammals

dentary squamosal joing

Middle ear

mammals- stapes, malleus, incus

reptiles-stapes

transmitting vibrations to sensory structure

Teeth (mammals)

-heterodont teeth

-teeth that differ in form

-deciduous and permanent

-varied definition based on diet

Mammal characteristics

-amniotes

-endothermic

-high metabolic rate

-most are nocturnal

-sensory adaptations

occlusion

bottom teeth match with top

Heterodont teeth

teeth that differ in forms. opposite of homodont

Reproductive cycles (mammals)

Males fertile at any time

Females:

-estrous cycle (heat)

-menstrual cycle

Estrous cycle

-heat

-seasonal

-receptive only during brief time

Menstrual cycle

receptive throughout the cycle

Monotremes (Subclass Prototheria)

-egg laying mammals: no gestation

-only 5 extant species

-duckbilled platypus and echidna

-only Australia and new guinea

-most primitive group of mammals

-short incubation time with yolk

-tuft of hair for milk

-cloaca

-oviparous

Marsupials (subclass Theria, Metatheria)

-kangaroos, koalas, opossums

-south America and Australia

-short gestation (1-2 weeks)

-prolonged lactation

-simple placenta so viviparous

-marsupium: pouch

Placentals (subclass Theria, Eutheria)

-amniotic egg

-found worldwide

-long gestation

-advanced placenta- young complete embryonic development in uterus of female

-precocial or altricial

-moms energy during gestation

Precocial

able to move and be independent right after birth (horses)

Altricial

still need extensive care from mother after birth (humans)

Placentals v marsupials

-placentals reproduce at faster rate, especially at smaller body size

-placentals are far smarter; larger brains for body size

-females in each invest much in young, but at different times/rates

1) marsupials: lactation

2) placentals: gestation

-marsupials have low species diversity

Whales and artiodactlys

even toed mammals

-returned to sea about 50mya

-fossil whales have artiodactyl ankles

Measuring biodiversity

1) species richness: total number of species w/in an area

2) genetic diversity: total variety of genes w/in a single species

3) endemic species: species that occur here and nowhere else

4) ecosystem diversity: total number of ecosystems in the region

Ecosystem importance

-aesthetic and ethical

-pharmacological

-loss of unique organisms- extremophiles

-overall earth health

-ecosystem services:

purification of air/water

erosion control, reduction of flooding

-soil composition

-nutrient cycles

-balance of pests and plagues

The biodiversity crisis

-land surfaces altered by humans

-freshwater used by humans

-current extinction rates are higher

-30,000 species per year go extinct

Threats to biodiversity

1) habitat destruction & fragmentation

2) introduced species

3) climate change

4) overexploitation

5) pollution/light/noise

Disruption of food chains

-hard to predict what happens when one or more species are removed/ added to the food chain

Extinctions

-typically followed by rebound

-new niches to fill

-disaster species thrive in disrupted areas

-large number of species go extinct at the same time in a global pattern

-background/previous

Anthropocene

a proposed geological epoch dating from the commencement of significant human impact on earth's geology and ecosystems, including, but not limited to, anthropogenic climate change

Preserving our world

-off-site preservation: zoos, aquaria, botanical gardens, seed banks

-educational awareness

-research/genetic pool

-habitat corridors (green bridges)

Re-introduction

create a new population in original habitat

issues:

-try to ensure genetic appropriateness

-solve initial problem

-behavior (training)

-does ecosystem still work?

-low success rate

-expensive

Preserves

factors to consider:

1) how to choose

2) how to manage

3) size

4) how to protect

5) human use

6) funding

Introduced species

-disruption of food chain

- no natural predators

-can outcompete

-unexpected consequences

Climate change

-unpredictable weather patterns

-hardiness zones

-breeding timing

-light signals

-food sources

-temp cues

Fragmentation

when habitats are split apart and surrounding areas are degraded

background extinction

normal number of extinctions