Intro and taxonomy Flashcards
Moving from land
can’t breathe underwater, increased loss of heat through integument, viscosity, altered characteristics of sound propagation, low light conditions
3 orders of marine mammals
Cetacea, Sirenia, Carnivora
Features they share (5)
- occupy/rely on marine habitats (degree of adaptation relates to amount of time spent in water)
- similar anatomical features: large body size, streamlined shape, insulation (blubber or fur, or both), decrease in presence and size of appendages
- similar physiological adaptations to thrive in aquatic environment (e.g. diving, thermoregulation, orientation)
- Most/many are, or have historically been, deliberately exploited.
- others decimated by incidental takes and habitat destruction/ modification
Cetacea shared characteristics
- breathe through nostrils on top of head
- breath hold capacity - increased
- thick blubber
- large size
- vascular heat exchange system
- smooth skin
- reduction of appendages
- broad, horizontal tail flukes
- dorsal fin
- some (odontocetes) have advanced sound processing capabilities
Sirenia shared characteristics
- paired nostrils; anterior on head
- dense skeletal bones
- no echolocation/less sensitive hearing
- dentition - mastication
- moderate size (excluding Steller’s sea cow – 8 m/7000 lbs)
Pinniped shared characteristics
- modified hind limbs
- most have dense fur
- streamlined, fusiform body shape
- dentition - differentiated teeth
- rely primarily on vision and touch (vs. sound)
- exceptional diving capabilities
- moderate size (largest: elephant seal – 4 m/5000 lbs)
Polar bear intro
- capable of slow, sustained swimming 2. hollow hair fibers (buoyancy)
- long legs
- specialist predators of seals
Sea otter intro
- eat benthic molluscs and crustaceans
2. hind feet - large, flipper-like
3. one of thickest coats in animal kingdom
Mysticeti intro
• 14 species
size: blue whale - pygmy right whale (6.1 m)
• sexual dimorphism - females larger
• two blowholes
• filter feeders - gulpers vs. skimmers
• teeth replaced by baleen - triangular plates of fibers (keratin); diameterdiet
• passive feeders - less developed musculature
Balanopteridae intro
sleek - “greyhounds of the sea”
- dorsal fin: present and inversely proportional to size
- long, distinct ventral grooves
- baleen short and wide
Balaidae intro
large with huge mouths
- no dorsal fin
- no throat grooves (true filter feeders) - baleen is longest of all mysticetes
- callosities
Neobalaenidae intro
smaller and sleeker with similar head shape - falcate dorsal fin
Eschrichtidae intro
2-5 throat grooves
- small dorsal fin followed by ridges/knuckles
- unique bottom feeding (suck food and water in)
Odontoceti intro
approximately 70 species (10 families)
• whales, dolphins (including river dolphins), and porpoises • great range in size (largest = sperm whale males = 15 m) • all have teeth but not erupted in some
• single blowhole (offset to L)
• echolocation
• sexual dimorphism - males larger (in most cases)
- Family Physeteridae - sperm whale
- extreme sexual dimorphism
- deep divers (2000+ m/90+ min. breath hold)
- short/squat dorsal followed by ridges
- huge head spermaceti organ (NOT homologous to the melon)
- Family Kogiidae - dwarf and pygmy sperm whales (2 living spp.)
- smaller (3.3 m and 2.7 m)
- v. similar appearance/different proportions - distinctively short heads
- spermaceti organ
- Family Monodontidae - narwhal and beluga
- no dorsal fin
- Monodon monoceros - male - long, spiraling tusk (tooth)
- Delphinapterus leucas - all white color; peg-like teeth; “sea canary”
Family Ziphiidae - beaked whales
- small - medium with narrow rostrum
- notch in flukes lacking
- 2 throat grooves - “V”
- 2-4 teeth (severely reduced dentition); erupt in males
- ex. Strap-toothed whales (Mesoplodon layardii) – two flattened teeth curve over rostrum
Family Delphinidae - largest and most diverse group (~ 35 spp./17 genera)
- range from smallest (Hector’s = 1.2 m) to largest (killer whale - 9m)
- “blackfish” - colloquial name for 6, similar species: killer whale, false killer whale, pygmy killer whale, 2 pilot whales, melon-headed whale (dark color, decreased dentition, no beak)
- rest share typical “dolphin” shape: distinct beak, prominent dorsal, 20+ pairs of teeth; 2+ fused vertebrae
- ex.s - Cephalorhynchus spp. (4 of them), northern and southern right whale dolphins, Irrawaddy dolphin
Family Phocoenidae - porpoises (6 species)
- small and lacking beak
- spatulate teeth
- small (or no = finless porpoise) dorsal
- Families of river dolphins (one species each)
- Family Platanistidae (South Asian river dolphins) – Platanista gangetica 8. Family Iniidae (Amazon river dolphins) – boto; differentiated dentition! 9. Family Lipotidae (Chinese river dolphins) - baiji
- Family Pontoporiidae (La Plata dolphin)
Family Trichechidae - manatees
- Trichechus manatus (West Indian manatee), T. senegalensis (West African manatee), and T. inunguis (Amazonian manatee)
- slow moving (fluke - paddle), warm water, herbivorous - maneuverable forelimbs
Family Dugongidae - dugongs
- more well-developed musculature - flukes more dolphin-like
- obligate bottom feeders
- males have pair of tusks
Family Odobenidae - walrus (1 species; 2 subspecies)
- long, external tusks (males and females - sexual dimorphism) - highly enervated muzzlebottom feeders
- thick, warty skin (~ 4 cm) and ample blubber (5-10 cm)
- no external ears
Family Otariidae - eared seals (fur seals and sea lions) - 16 spp./7 genera
- external ear flaps (pinnae)
- long, hairless flippers with splayed digits and vestigial nails - rotatable hind flippers - “walk” on land
- pronounced sexual dimorphism and polygynous
Family Phocidae - true seals - most diverse (13 genera)
- lack pinnae
- shorter, haired forelimbs
- non-rotatable hind limbs
- less pronounced sexual dimorphism - highly diverse color patterns
Family Ursidae - polar bears
- hollow, transparent fur/black skin and thick blubber
- continuous swimming; limited diving
- streamlined compared to terrestrial bears (no should hump, small ears and head, long neck)
- large paws with non-retractable claws
Family Mustelidae - sea otters
- extremely dense fur
- skin flap for food storage - horizontally flattened tail - can dive up to 180 ft
