Cetaceans Flashcards
Cetacea is an Order of animals which includes ….
Whales, dolphins, and porpoises. Millions of years ago the ancestors of modern cetaceans were predatory land mammals, but due to unknown pressures they made the return to the sea approximately 60 million years ago and are now completely aquatic. This is why phalanges and vestigial pelvic bones can still be found in cetaceans (can be used for demonstrating similarities between humans and whales. Another similarity is we are both mammals)
Acronym to remember the characteristics of mammals
WHALE
W - Warm blooded Cetaceans have a four-chambered heart to circulate their warm blood
Cetaceans have thick blubber layer to reduce the amount of heat loss
Blubber is an insulator, streamlined, and source of energy during migration
H - Hair. All Cetaceans have hair at some point in their development and some retain it
Throughout their lives. The bumps visible on a humpback’s rostrum or nose are hair follicles
A - Air Breathers. Cetaceans’ breathing is voluntary and requires conscious effort, unlike ours.
Whales can only breathe through their blowholes, not their mouths, because their trachea
(Airway) does not connect to their esophagus (throat).
L - Live Birth. Whales give birth to live young. Cetaceans young are much more capable than
Human young and must begin swimming immediately.
E. - Eat/Drink milk. Whales nurse their young. Cetacean milk is generally very high in fat to
Begin building the baby’s blubber layer and has a very thick consistancy.
Whale Births
Length of Gestation
Gray whale Minke whale Humpback whale Killer/Orca whale Harbor porpoise Dall's porpoise Pacific white-sided dolphin Bowhead Gray whale Minke whale Humpback whale Killer/Orca whale Harbor Porpoise Dall's Porpoise Pacific white-sided dolphin Sperm whaleBowhead Gray whale Minke whale Humpback whale Killer/Orca whale Harbor Porpoise Dall's Porpoise Pacific white-sided dolphin Sperm whaleBowhead Gray whale Minke whale Humpback whale Killer/Orca whale Harbor Porpoise Dall's Porpoise Pacific white-sided dolphin Sperm whale
Gray whale - 13 mos
Minke whale - 10 - 11 mos
Humpback whale - 11 - 12 mos
Killer/Orca whale - 15 - 18 mos
Harbor porpoise - 10 - 11 mos
Dall’s porpoise - 10 - 12 mos
Pacific white-sided dolphin - 12 mos
Whale Births
Duration of Nursing
Gray whale Minke whale Humpback whale Killer/Orca whale Harbor porpoise Dall's porpoise Pacific white-sided dolphin
Gray whale - 7 - 9 mos
Minke whale - 4 - 6 mos
Humpback whale - 10 - 11 mos
Killer/Orca whale - longer than 12 mos
Harbor porpoise - 8 - 12 mos
Dall’s porpoise - approx 12 mos
Pacific white-sided dolphin - 8 - 10 mos
Aquatic adaptations
Body shape and form: Teardrop shape and smooth skin allow easy movement thru H20
External appendages (ears and genitalia) encapsulated within
body to reduce drag.
Vertebrae interlock and cervical, or neck, vertebrae are short, or in
some cases, fused to provide support for powerful swimming.
Tale is used in an up-and-down motion, unlike sharks.
Dorsal fins provide stability and can be used to thermoregulate by
By being thrust above the surface of the water.
Keeping warm: Besides blubber, cetaceans use a special circulatory system to retain
heat. They lose less heat when breathing because their blood
retains more O2 than ours.
During deep dives, their system can limit blood flow to extremities,
such as flippers, so there is a large supply of blood for vital organs.
Their veins and arteries are arranged in a parallel pattern so that warm
blood is circulated next to cooler blood and heat is exchanged.
Whales have a lower surface area relative to their body mass.
They have a fast metabolism and must eat a great deal every day.
Some whales have to migrate to warmer waters to give birth.
Breathing. Lung volume is proportional to body mass, but the amount of O2 an
animal needs is proportional to surface area, so as an animal’s size
increases, their storage ability increases faster than their O2 needs.
This means whales do not need large amounts of O2 despite their size
Cetaceans replace about 90% of the O2 in their lungs with each
inhalation, compared to our 10%, replacing O2 more quickly, but also
more infrequently.
Whales can store O2 in their muscles, which can also function for
longer without O2.
When diving, their heart rate drops dramatically. They take very little
air with them when diving, so little gas is dissolved in the blood,
greatly reducing the risk of nitrogen buildup and the “bends”.
Communication/Navigation Light does not penetrate very far beneath the surface.
Seawater is 800 times denser than air and transmits sound much
More efficiently.
Whales can send out calls that are heard thousands of miles away
Not sure how Baleen whales achieve this as no vocal cords.
Toothed whales use echolocation to map environment
Sounds are produced by air sacs that branch off from the airway
Within the cranium.
A soft tissue, oil filled melon, acting as an acoustic lens, sits on the
front of the cranium in front of the air sacs, which can be
opened and closed at will by the whale and emit pulses which
are focused out through the melon.
The sound bounces off of objects and are received through oil-
filled reservoirs in the lower jaw.
The sound is conducted through the jaw to the ear and then to the
brain.
Whales read reflected sound similar to the way we read reflected
light with our eyes.
They can use sound to perceive distance, depth, size, shape,
texture, and speed.
Whales in groups can receive the sounds their companions have
produced to map their surroundings
Dive Comparisions - Avg Dive Time
Pacific White-sided dolphin Killer/Orca whale Humpback Gray whale Blue Whale Sperm Whale
Pacific White-sided dolphin. - 6 min
Killer/Orca whale. - 5 - 10 min
Humpback. - 15 - 30 min
Gray whale. - 5 min
Blue Whale. - 5 min
Sperm Whale - 40 min
Dive Comparisions - Avg Dive Depth
Pacific White-sided dolphin Killer/Orca whale Humpback Gray whale Blue Whale Sperm Whale
Pacific White-sided dolphin. - Approx 600 feet (182 yards)
Killer/Orca whale. - 300 - 800 feet (91 yards - 242 yards)
Humpback. - 500 feet (152 yards)
Gray whale. - 200 - 400 feet (61 yards - 121 yards)
Blue Whale. - 300 feet (91 yards)
Sperm Whale - 3900 feet (1,181 yard, 12 football fields)
Whale senses compared to humans
Essentially the same as ours BUT
Sight: Less important to whales than it is to us and is mostly used at or near the surface.
Most cetaceans have good eyesight, but the placement of their eyes on either side of
their head means that they likely do not have stereoscopic vision like humans do and
perceive depth differently.
Smell: Cetaceans have either a limited sense of smell or none at all
Toothed whales lack olfactory bulbs in the brain entirely
Smell is less important for detecting prey in the water than it is on land.
Touch: Cetacean skin is very sensitive and physical contact between whales is common
Orcas have also been observed rubbing themselves on rock beaches and playing
With kelp, both of which are presumed to provide tactile stimulation.
Taste: Not much is known about whales’ sense of taste, although it has been shown that
Dolphins do have a sense of taste.
Hearing: Sound is incredibly important to cetaceans and hearing is highly developed in whales.
Aside from the echolocation toothed whales use to navigate, whales use calls to
communicate with each other, coordinating hunting prey, and finding mates.
Theories also suggest that whales navigate using the earth’s magnetic field but nothing is known and no studies have been published
Whales spend …. of their time at the surface
3%
Individual identification is important to
Establishing population numbers
Behavior over time
Other factors to make research easier
Whales can be identified by
Unique colorations
Placement of nicks and scars
Other methods
Whale distributions
Bowhead Gray whale Minke whale Humpback whale Killer/Orca whale Harbor Porpoise Dall's Porpoise Pacific white-sided dolphin Sperm whale
Bowhead. - Arctic and sub-arctic; mainly at the edge of the ice fields.
Not seen in the Salish Sea, but the museum displays a
few bowhead baleen specimens.
Gray whale. - Primarily coastal in the North Pacific; high latitude in summer; low
latitude in the winter.
Minke whale. - A cosmopolitan species; found particularly in coastal temperate
waters.
Humpback whale. - All temperate and tropical seas; high latitude in the summer, low
latitude in the winter. Seen in the Salish Sea after their
migration to Baja to give birth.
Killer/Orca whale. - Genuinely cosmopolitan; tend to prefer cool coastal waters.
Members of both the resident and transient ecotypes are
regularly seen in the Salish Sea.
Harbor Porpoise. - Cold temperate and sub-arctic waters of the Northern
hemisphere; general coastal. Population in the Salish Sea is
quite healthy.
Dall’s Porpoise. - Confined to the North Pacific; north of 36 degrees north. Have
been seen less frequently in the Salish Sea lately.
Pacific white-sided dolphin. - Generally temperate pelagic waters of the North Pacific. Not
truly an inhabitant of the Salish Sea, but occasionally seen
traveling briefly through it in large numbers.
Sperm whale. - All oceans except polar ice fields; dependent on season and
sexual status. Not seen in the Salish Sea, but the museum
displays a few sperm whale teeth.
The group Cetaceans can be further broken down into two groups, or suborders, of whales…
Mysticetes - Baleen Whales
Odontocetes - Toothed Whales
Differences between Mysticetes (Baleen) and Odontocetes (Toothed)
Mysticetes (Baleen) -
Baleen present as adults
Two Blowholes
Symmetrical skull
Female usually larger than male
Do not use echolocation
Mandible not fused (not symphyseal)
Rigid thorax
Usually four digits in pectoral flipper
Large tongue
Wax ear plug in the ear canal
Inner ear bones connected to skull
Weak connection of ribs to sternum
Tend to be solitary or in small groups
Generally migrate from cold feeding grounds at the extremes of the globe to warm waters to
give birth and breed.
Journeys can be thousands of miles long
Odontocetes (toothed) -
Teeth always present One blowhole Asymmetrical skull Males usually larger than females Use echolocation Mandible fused anterior lay (symphyseal) Mobile thorax, for collapse during deeper dives Always five digits in pectoral flipper Small tongue No wax ear plug in the ear canal Inner ear bones not connected to skull Stern also segments always present in ribs Lack molars and instead of chewing tear and gulp their food Includes dolphins and porpoises
Baleen characteristics
- Keratin (same protein that forms hair and fingernails.
- It continues to grow throughout a whale’s life, and edges wear down over time.
- Consists of a series of plates which line only the upper jaw of the whale; inner edge densely
fringed - Used to strain the whales’ prey out of the water.
- Prey mostly small shoaling fish, krill, and zooplankton.
- Food is licked off the back of the baleen with the tongue and swallowed.
- Because prey so small baleen whales’ throats are small
Mysticetes (Baleen) Whales include…
Minke whale
Humpback whale
Gray whale
7 species of whales known as rorquals, defined by their many ventral grooves on their throats allowing their throat to expand and hold large amounts of H20 before straining food Found in Salish Sea- Minke Humpback Gray
Found outside of Salish Sea- Fin ? ? ?
Odontocetes (Toothed) whales include …
Dall’s Porpoise
Harbor Porpoise
Pacific White-sided dolphin
Orca/Killer whale
Number of Baleen plates-
Bowhead Gray Minke Fin Humpback
Bowhead. - 325 - 360 Gray. - 138 - 180 Minke. - 288 - 300 Fin. - 262 - 473 Humpback. - 270 - 400
Size of individual plates -
Bowhead Gray Minke Fin Humpback
Bowhead. - L 10-14 ft, W 12-16 in
Gray. - L 16-20 in, W up to 10 in
Minke. - L up to 13 in, W up to 5 in
Fin. - L 27-30 in, W 12 in
Humpback. - L 31-34 in, W 6 in
Ventral Grooves -
Bowhead Gray Minke Fin Humpback
Bowhead. - None
Gray. - Usually 2, 6 in long, only on throat
Minke. - 15 - 25
Fin. - 50 - 100, grooves extend to the navel
Humpback. - 20 - 50, extend slightly beyond the navel
Color/Description of Baleen -
Bowhead Gray Minke Fin Humpback
Bowhead. - Dark gray to black; bordered by lighter fringes
Gray. - Yellowish-white; Plates on preferred side wear faster
Minke. - Front plates yellowish to white; back are dark
Fin. - Left side dark; right side striped yellowish and bluish gray; white toward the back
Humpback. - Usuallyblack; young whales’ may be lighter
Number of teeth -
Killer/Orca Harbor Porpoise Dall's Porpoise Pacific White-sided Dolphins Sperm
Killer/Orca. - 46 - 50
Harbor Porpoise. - 88 - 108
Dall’s Porpoise. - 78 - 94
Pacific White-sided Dolphins. - 92 - 128
Sperm. - 36 - 50
Minke Whale - Balenoptera - acutorostrata
Max Length: about 35 feet (8-11 ft at birth)
Max Weight: about 10 tons
Life Span: estimated at 50 years, but uncertain
Description:
- Dark gray or black in color
- White bands on pectoral fins
- Swaths of lighter color on sides
- Small crescent-shaped dorsal fin
- Generally observed in slow paced (one knot) surfacing behavior with subtle blows; often exposing the top of its head
Humpback Whale - Balaenoptera - novaeangliae
Max Length: up to 60 feet (about 15 ft at birth)
Max Weight: up to 40 tons
Life Span: at least 50 years,
Description:
- Slate gray or black in color
- Long pectoral fins (about 25% of entire body length)
- Pectorals have a scalloped leading edge
- obviously audible and visible blows; often display percussive behaviors at the surface
- Dorsal fins seem mutated and range from sickle to triangular shaped; dorsal ridge has
knuckle-like bumps - Irregular patterns of hair follicles on the head and jaw, parasites such as barnacles and lice
create scarred patterns on the skin - Often will surface numerous times, then dive deep, raising the tail out of the water
