-mother produces milk for their young

-parental care is most advanced

-brain greatly advanced over reptiles and birds.

-cerebrum and cerebellum are greatly enlarged

Anatomical Characteristics of Mammals

skin, body, and skeletal

-skin is rich in sweat glands (sweat, sebaceous, mammary)

-four regions of the body (head, neck, body, tail)

-most are quadrupeds (except cetacea=whales and dolphins, and sirenia=seacow)

-presence of hair (except whales, hippopotamus, elephant, rhino, etc.)

-skeletal differences from lower vertebrates

*epiphyses---limit final growth

*attachment of skull and mandible

*mammals are the only animals with teeth set in sockets (except for crocodile)

Anatomical Characteristics of Mammals

(inner body, organs, feeding habits, reproduction)

-presence of a muscular diaphragm=important for breathing

-lungs hang freely in cavity of chest

-homeothermic=about 99 degrees F - i.e. in humans

-Non-nucleated RBC

-some are carnivores

-some are herbivores

-some are omnivores

-VIVIPAROUS

-ova are small and yokeless, *except in Monotremata

Monotremes

(3 species)

-oviparous

-duck-billed platypus

-spiny anteater

Viviparous

Marsupial

-young attached by primitive placenta

-short gestation, then continue "gestation" in the marsupium (pouch)

-about 280 species

-Joey by hand, one in pouch, one in uterus

the time from fertilization to birthing

-camouflage

-insulation

-protection (abrasion, sunburn)

-sensory organs

-communication

           *announce presence

           *communicate social information

           *gender

-True Placental Animals

          -all other mammals (about 4,300 species)

          -young attached to mother by a complicated placenta

         -gestation lasting from a few weeks (rodents) to 22-24 months (elephants)

-tissue develops from embryo

-tissue is parallel to uterine wall

-vascular systems are side-by-side so nutrients and washes transport across

-developing fetus is somewhat protected

-most are terrestrial

-some are burrowers

-some are arboreal

-some are acquatic

-some fly

-some are diurnal

-some are nocturnal

• Walking and running
  • Plantigrade = bear, human, etc= walking on sole of foot
  • Digitigrade (cat, dog, etc)= walks on toes
  • Unguligrade (hooved animals)=walks on hooves
• Leaping--rabbits, hares, gerbils
• Climbing--squirrels, monkeys
• swimming
  • paddle with limbs = volves, platypus, dogs, humans, etc
  • use tail = otters, beavers, etc
  • tail only = whales, dolphins, etc
• parachuting-- some marsupials, rodents and insectivores
• flying--bats, flying foxes

• Largest mammalian order
• Mammals with four special teeth
  • 2 upper and 2 lower chisel-like incisors
  • also back teeth for chewing
• Generally herbivorous (with exceptions)
• Examples
  • rats, mice, gerbils, hamsters, cavies, chinchillas
  • NOT bats, badgers, ferrets or rabbits

Rodents

(feed, young, reproduction)

• most will feed on seeds or alfalfa pellets
• teeth need to be worn down
• young are 'pups' and most are altricial
• most have very short reproductive cycles and gestation periods

• a numerous species
• NOT INDIGINOUS TO N. AMERICA
• Can be very destructive
• have a very good sense of smell
• reproduce very quickly
• nocturnal

• Club in England since 1800
• First club in US in 1950
• Mouse shows are divided into 7 varieties based on coat type and 5 sections based on color
• Clubs in IL, MI, maybe WI

Gerbils

• Same family as hamsters
• native to deserts of Asia, Africa, Europe
• pets are usually Mongolian gerbils
• hop around like kangaroo
• desert animals, so drink very little water
• very little odor
• nocturnal
• can be left alone up to a week
• short-lived
• reproductive life often ends quickly
• seizures are fairly common (20-40%)

• short-tailed gerbils (sort of)
• most pets are Golden (syrian) hamsters
• have internal cheek pouches which they stuff with food
• generally dont get along with other hamsters
• two males MAY be able to live together
• two females will usually fight
• male and female will get along for mating, then fight

• Native to South America
• Raised as a food animal there
• male=boar, female=sow
• physical characteristics
  • 'football shaped'
  • no tail
  • short legs, 4 toes on front and 3 toes on back feet
  • heavy skull

•  
  • cacannot handle cold weather
• need to be kept above 32 degrees
• differences in reproduction
  • usually only 2-3 per litter
  • pups are precocial
  • can have breeding groups (1 boar, 5 sows)
• Sows need to be mated before 6 months or not at all
• Housing
  • can be simple
  • can be outdoors in summer with ample shade
• Feeding
  • lots of fiber (alfalfa cubes, etc)
  • grass hey
  • cecum is well-developed
  • add a salt ring to lick
  • require vitamin C

• Bushy tail like squirrel
• known for their soft fur
• native to Andes Mountains
• need to be kept cool
• often are nervous, though some can be calm
• need a bath every few days
• reproduction
  • can group mate (1male: up to 7 females)
  • small litters=2 on average
  • young are precocial
• inbreeding has caused some problems

-Puberty: The period during which secondary sex characteristics begin to develop and the capability of sexual reproduction is attained

-long bone growth stops (epiphyses closes under influence of estrogen)

• Puberty (aggression, territoriality)
  • Weight approx. half that of adult animals
  • immature female vagina is closed (hymen)
  • Vagina opens at puberty
  • testes descend into scrotum of the male
  • behavioral changes
  • vocal changes
  • change in pheotypic appearance

• Rats and mice are polyestrus
• cycle from puberty until senescence
• average length of cycle is 4-5 days
• able to be mated and multiply quickly

The estrus cycle is divided into four cycles: proestrus, estrus, metestrus & diestrus

• FSH (follicle stimulating hormone) level increases
• FSH is from the anterior pituitary gland
• some follicles begin to grow and mature
• stimulated follicles produce estrogen
• estrogen produces secondary sexual development

• FSH and estrogen levels high
• Progesterone level is low
• Only time female will accept male
• Surge of LH (lutenizing {turning yellow} hormone) occurs
• LH is also from the anterior pituitary gland

• follicle opens and releases ovum
• rats and mice are spontaneous ovulators
• contrast to induced ovulators?

Diestrus--period before next proestrus (2 days)

• corpus luteum (CL) forms in raptured follicle
• progesterone (stops further reproduction cycle) level is high (secreted by CL)
• If no pregnancy, CL regresses and new cycle begins
• Prostaglandin causes CL regression

THERE ARE CYCLIC CHANGES IN VAGINAL EPITHELIUM DURING THE CYCLE OF RODENTS

• Nocturnal Breeders
• Many intromissions before ejaculation
• spontaneous ovulators vs induced
• May mate 12-20 times in a 12-hour period
• If there is an infertile mating pseudopregnancy may last 13-16 days
• a 2year old mouse or 3yr old rat is quite old

• Mouse 19-21 days; Rat 21-23 days
• No cyclic changes in vaginal epithelium during pregnancy
• Changes in mammary gland apparent after 14 days of pregnancy -- not important
• Fetuses can be palpated through the abdominal wall
• Mucous and blood discharge from vagina 1-4 hours before partuirtion--- giving birth
• parturition comeplete in four hours---pupping (birthing)

Postpartum and Lactation

Rats and mice

• an immediate postpartum estrus in mice and rats (willing to be mated right away)
• lactation for three weeks
  • If there is a new pregnancy the gestation is longer and the lactation is shortened
• Average little size in mice is 4-7 and rats 6-10
• young can be sexed by distance between the anus and the genital papilla. Male 2x

• Induced ovulators
  • what other animals are induced ovulators
  • precocial (hare)
  • altricial (rabbit)
  • both make nest from ventral fur
  • can not retrieve young

- average of 28 days (range 21-35)

- day 1 (first day of menstrual flow)

- follicular phase days (1-13)

- day 14 ovulation (LH)

    - day 14-15 fertilization

    - egg picked up by fimbria of fallopian tube

- day 20 implantation

- day 14-28 luteal phase (progesterone)

Hormones

Estrogen

• • produced by cells in the follicle
  • necessary for development of secondary sex characteristics in the female
  • stimulates estrus (heat)
  • positive and negative feedback

Hormone

FSH

-produced in the pituitary

-acts on the ovary to stimulate growth of follicles

Hormones

(LH) Luteinizing Hormone

-produced by pituitary

-stimulates sex steroid hormone production

-causes ovulation

Hormones

Progesterone

-produced by corpus luteum

-acts at the pituitary to block the LH surge thus preventing ovulation

-maintains pregnancy

-destroys the corpus luteum

-stimulates production of relaxin

-produced by the posterior pituitary

-causes uterine contractions

-relaxes the cervix, pelvic bones

-blood level increase prior to the onset of labor

-stimulates milk release

-initiates milk secretion after parturition

-stimulates maternal behavior

Rabbits and Hares

order

family

-order=lagomorpha

-family=leporidae

-characterized by large front teeth, but with small teeth behind the uppers