Suborder Cetacea Flashcards
Cetacea is Fully adapted to aquatic life.
- Feed at the middle or top of marine food web
* Ability to echolocate
• First whales from Eocene (~50 MYA) of Tethys Sea
– Transitional semi-aquatic forms
– Lacked baleen, had teeth
– Large eyes—suggests they hunted fish
Some later forms (Mysticeti) had both teeth and baleen
• Limited bulk filter feeding possible
Middle Miocene mysticetes lost teeth
- Elongate rostrums to support more baleen
* Bulk filter feeding
• Odontocetes (toothed whales) sister to
mysticetes
Cetacea • Thick layer of subcutaneous blubber
• Testes remain abdominal
• Vertebrae with high neural spines
• Teats enclosed within slits next to
urogenital opening
Cetacean Adaptations • Must breathe air – Able to alternate between – Rapid rates of – Twice the – 2–9 times – Blood bypasses • Blood flow to brain – Tolerate high levels
–periods of eupnea and apnea – gas exchange in lungs – number of red blood cells –as much myoglobin – certain muscles during diving • maintained – of lactic acid
Cetacean Adaptations • Deep diving adaptations – Many ribs lack connection to sternum – Lungs dorsal to – Volume of non-vascular air spaces – Trachea short and – Bronchioles braced by
– lungs collapse at depth – diaphragm – is large – large in diameter – cartilage rings
Cetacean Adaptations • Swimming adaptations – Sub-dermal “springs” in tailstock – Drag reduced on body surfaces – Larger body mass increases speed
– store and release elastic energy – Compliant spongy layer in outer skin dampens pressure and turbulence – more favorable for thermoregulation
Mysticeti Baleen whales
- Found in all oceans
* Populations decimated by whaling
Mysticeti • Three distinct feeding modes
– Grazing near surface – right whales
– Lunge feeding – rorquals
– Bottom scraping – gray whale
Family Balaenidae
are
• Right whales and bowhead whales
Family Balaenidae
• Huge head and tongue
- Flippers short and rounded
* Dorsal fin absent
Balaenidae – grazing
near surface
Family Balaenopteridae
are
lung feeding Rorquals
Family Balaenopteridae Baleen plates
short and broad
Family Balaenopteridae have pleated or furrows throat
allow vast expansion of
throat during feeding
Family Balaenopteridae have throat pouch contracted
water and food
pass through baleen plates
Family Balaenopteridae Mandible braced
by fronto-mandibular stay apparatus
Family Balaenopteridae may also use bubble nets
– Swim below school of prey
– Circle prey while emitting constant stream of
bubbles
– Swim rapidly up through middle of bubble net
– Engulf prey at surface
Family Eschrichtiidae are
gray whale and are from • Parts of North Pacific
Family Eschrichtiidae have Small head
short baleen plates
Family Eschrichtiidae
exhibit third style of feeding
- Plow head through mud at bottom
- Scoop or suck up sediments
- Filter out marine organisms from bottom
Family Odontoceti are
- Toothed whales, porpoises, and dolphins
* All oceans and seas, and some river systems
Family Odontoceti teeth don’t occlude
• Homodont and monophyodont
Family Odontoceti echolocate
some may stun prey acoustically
Family Delphinidae are from
• All oceans and some large rivers
Family Delphinidae have a
Fatty-deposit “melon” sits above and
behind snout
Family Delphinidae • Rapid swimmers, regular leaps
• Highly gregarious
– Form schools
– Highly vocal
– Cooperative behaviors in some species
– Intelligent
Family Monodontidae are from
Arctic Oceans, Bering and Okhotsk seas, Hudson
Bay, and St. Lawrence River
Family Monodontidae • Narwhal (Monodon monoceros) – • Beluga (Delpinapterus leucas) –
- long, straight, forward-directed tusk
- white whale
Both species:
– Gregarious
Family Phocoenidae are
porpoises
Family Phocoenidae have short jaws and no beak
- Dorsal fin low or absent
* Form schools
Family Physeteridae are
sperm whale
Family Physeteridae • Huge blunt head
(one third total length)
Family Physeteridae • Rostrum contains oil sacs—spermaceti organ and junk
• Oil important in former whaling industry
Physeter of Family Physeteridae: – Social—groups of up to – Schools usually contain – Younger males form – Use powerful echolocation signals at – Feed on
– 1,000 individuals – one or more large males – “bachelor” schools – great depth – giant squid and fish
Family Ziphiidae are
beaked whale
all oceans
Family Ziphiidae have a single
lower tooth on each side on some
species
Family Ziphiidae stomach
divided into 4–14 chambers
Family Ziphiidae eat squid and deep-sea fish
• Teeth may be used primarily during
intraspecific social interactions, and of little
use during feeding
River dolphins
- Family Platanistidae
* Family Iniidae
Family Platanistidae are from
– Southern Asia
Family Platanistidae
– Eyes are reduced
Echolocation important in murky waters
– Tend to swim on sides
Family Iniidae
– Amazon River dolphin (or boto)
– La Plata River dolphin (franciscana)
– Chinese river dolphin (baiji – extinct?)
- Inia geoffrenis
- Pontoporia blainvillei
- Lipotes vexillifer
- Yangtze River
