The Life of Mammals
Mammals (class Mammalia) are a clade of warm-blooded amniotes. Among the features that distinguish them from the other amniotes, the reptiles and the birds, are hair, three middle ear bones, mammary glands in females, and a neocortex (a region of the brain). The largest group of mammals, the placentals, have a placenta which feeds the offspring during pregnancy.
Eurasian pygmy shrew (Sorex minutus).
Blue whale (Balaenoptera musculus)
Geographic Range Mammals can be found on all continents, in all oceans, and on many oceanic islands of the world.
Habitat Regions: • temperate • tropical • subtropical • polar
Terrestrial Biomes
Tundra Reindeer (Rangifer tarandus)
Taiga Eurasian elk (Alces alces)
Desert Lesser Egyptian Jerboa (Jaculus jaculus)
Savanna Aardvark (Orycteropus afer)
Rainforest Philippine Tarsier (Tarsius syrichta)
Mountains Аrgali, or the mountain sheep (Ovis ammon)
Polar icecap Рolar bear (Ursus maritimus)
One group (bats) have even evolved powered flight.
Aquatic Biomes
Muskrat (Ondatra zibethicus)
Steller sea lion (Eumetopias jubatus)
Walrus (Odobenus rosmarus)
Sea otter (Enhydra lutris)
Кiller whale (Orcinus orca)
Development
Monotremes Platypus (Ornithorhynchus anatinus)
Short-beaked echidna (Tachyglossus aculeatus)
Marsupials (Metatheria) Koala (Phascolarctos cinereus)
Placental mammals (Eutheria)
Reproduction
Mating System • • • monogamous polyandrous polygynandrous (promiscuous) eusocial
polygynous Plains zebra (Equus quagga)
monogamous European beaver (Castor fiber)
polyandrous Goeldi's marmoset or Goeldi's monkey (Callimico goeldii)
polygynandrous Common chimpanzee (Pan troglodytes)
eusocial Naked mole rat (Heterocephalus glaber)
Mammalian young are often born in an altricial state, needing extensive care and protection for a period after birth.
Most mammals make use of a den or nest for the protection of their young.
Some mammals, however, are born well-developed and are able to locomote on their own soon after birth.
Females feed their newborn young with milk
In addition to feeding their young, females must protect them from predators.
Lifespan / Longevity Mammalian lifespans range from one year or less to 70 or more years in the wild. Bowhead whales (Balaena mysticetus) may live more than 200 years.
Food Habits As a group, mammals eat an enormous variety of organisms. Mammals eat both invertebrates and vertebrates (including other mammals), plants (including fruit, nectar, foliage, wood, roots, seeds, etc. ) and fungi. Being endotherms, mammals require much more food than ectotherms of similar proportions. Mammals can be:
Carnivores (e. g. , species within Carnivora)
Herbivores (e. g. , Artiodactyla)
Omnivores
Locomotion styles are diverse. Mammals may:
swim
run
fly
burrow
climb
Sociality Social behavior varies considerably as well. Some mammals live in groups of tens, hundreds, thousands or more individuals. Other mammals are generally solitary except when mating or raising young.
Brown bears are mostly solitary.
A meerkat (Suricata suricatta) clan often contains about 20 meerkats, but some superfamilies have 50 or more members.
Numerous wildebeest during The Great Migratio
Activity patterns among mammals also cover the full range of possibilities. Mammals may be: • diurnal - active during the day • nocturnal - active during the night • crepuscular - active at dawn and dusk
Communication and Perception • • Sensory modalities in mammals: olfaction hearing tactile perception vision
Ecosystem Roles The ecological roles, or niches, filled by the nearly 5000 mammal species are quite diverse. There are predators and prey, carnivores, omnivores, and herbivores, species that create or greatly modify their habitat and thus the habitat and structure of their communities.
In part because of their high metabolic rates, mammals often play an ecological role that is disproportionately large compared to their numerical abundance. Thus, many mammals may be keystone predators in their communities or play important roles in seed dispersal or pollination. The ecosystem roles that mammals play are so diverse that it is difficult to generalize across the group. Despite their low species diversity, compared to other animal groups, mammals have a substantial impact on global biodiversity.