14 Marine Mammals I.Marine Mammals A.Sea otters (Order Carnivora) 1.Insulation a.Lack blubber b.Insulated by air trapped in fur c.Vulnerable to hypothermia.

14 Marine Mammals

I. Marine MammalsA. Sea otters (Order Carnivora)

1. Insulationa. Lack blubberb. Insulated by air

trapped in furc. Vulnerable to

hypothermia if fur becomes coated with oil 2. Hunted almost to extinction for their fur

Long before I came here, the N.W. Indians had hunted the otter along the whole length of the coast from Lower Cal. North, and they must have killed a very large number, as in early times they were so abundant that the Indians killed them with spears.

When I arrived here [1833], they were still quite plenty but they were soon hunted out. In hunting the N.W. Indians used buckshot and usually sent several canoes together so that they could almost surround an otter, thereby rendering escape almost impossible.

George Nidever, pp 45-46

In 1834, a hunter could obtain about $30 for a good quality sea otter pelt. By contrast, land otter brought a mere two dollars and beaver, which; was extensively hunted in the RockyMountains, brought only four dollars a pelt. (From the Introduction by Bruce Craig)

The Life and Adventures of George Nidever [1802-1883], Univ. Cal. Press, 1984

A. Sea otters (continued)

3. Eat 15-20 pounds of food (invertebrates) per daya. Devastating to commercial abalone and sea urchin fisheriesb. Remove large invertebrate herbivores and allow kelp forests to flourish

Typical Daily Consumption of a

Californian Sea Otter

Milne, 1995, Marine Life and the Sea, p. 232

Jade sculpture of a sea

otter eating a scallop

Photo by J. OBrien, June 2014

A. Sea otters (continued)

4. Intelligenta. Use rocks to crack open shellsb. Trapping program in Channel Islands

National Park(1)Difficult to catch more than once(2)Professional Navy divers

(a) Non-bubble releasing SCUBA gear(b) Come from below while animal sleeping

(3)Adults returned to original location

Sleeping Sea Otter

Castro & Huber, 2003, Marine Biology, p. 189

II. Marine Mammals (continued)

B. Order Sirenia1. Related to elephants2. Characteristics

a. Herbivoresb. No rear limbs

B. Order Sirenia (continued)

3. Manatees or sea cowsa. Freshwater and estuarine habitatsb. Tropical and sub-tropical habitatsc. Individuals who come this far north run risk of pneumonia in winter

3. Manatees or sea cows (continued)

d. Marine Mammal Sighting Network (1) Dr. Ruth Carmichael – DISL (2) https://www.facebook.com/mobilemanatees(3) http://manatee.disl.org

http://manatee.disl.or/

http://manatee.disl.or/

B. Order Sirenia (continued)

4. Steller’s sea cowa. Was found along Pacific Coastb. Ate kelpc. Whalers slaughtered them for

foodd. Scientists became aware of their

existence in 1741, they were extinct by 1768

e. Massive (= 10 tons)f. Major herbivore on kelp (impact

of extinction?)

Sketch of Steller’s Sea Cow made by Georg Stellerhttp://en.wikipedia.org/wiki/Georg_Wilhelm_Steller#mediaviewer/File:Extanstellersseacowea.jpg


Steller’s sea cow weighed about 10 tons and fed upon kelp in the Bering

Sea. Eaten by whalers, the last

individual was killed in 1768.

Steller’s sea eagle, Steller’s jay & Steller’s sea lion

http://en.wikipedia.org/wiki/Georg_Wilhelm_Steller

C. Pinnipeds1. Characteristics

a. Paddle-shaped flippers

b. BLUBBER: Thick hypodermal layer of fat that retains heat

C. Pinnipeds (continued)

2. Sealsa. Characteristics

(1) Rear flippers(a) Cannot be moved forward

(Pull themselves with front flippers when on land)

(b) Used for swimming only(2) No external ear

Seals (continued)

b. Elephant seal(1) Largest pinniped (2) Can grow to 4 tons

http://www.google.com/imgres?imgurl=http://4.bp.blogspot.com/-5W4nKGlD4rg/TtOyi0zQtBI/AAAAAAAACXc/C2JvEby6EE8/s1600/Northern%2BElephant%2BSeal2.jpg&imgrefurl=http://life-sea.blogspot.com/2011/11/northern-elephant-seal.html&h=1016&w=1524&sz=1670&tbnid=oGXX-UCdK20dbM:&tbnh=88&tbnw=132&zoom=1&usg=__5uqJ8z8guQogc7MGMycGKJ_8q28=&docid=RlFhTTMdLeY45M&sa=X&ei=AQy7Ufv4HYOK9gS6qIGoBA&sqi=2&ved=0CE8Q9QEwCw&dur=2330

Elephant Seal Haul-out off California Highway 1Photo: Jack O’Brien, June 2013


3. Sea lionsa. Characteristics

(1) Rear flipper can move forward(2) Anterior flippers assist in swimming(3) External ears(4) Long neck

b. “Fur” seals hunted almost to extinction in mid 1800's

Illustration showing anatomical differences between seal lions and seals



3. California sea liona. Barking “seals” trained to do tricksb. Protection has resulted in recent range expansionc. Nuisance

(1) Haul out on boat docks(2) Sushi bars and parasites

II. Marine Mammals (continued)

D. Cetaceans1. Characteristics

a. No hind limbsb. Tail ends in

horizontal FLUKES (Fish have vertical caudal fins)

c. BLOWHOLE: Nostrils on top of head

D. Cetaceans (continued)

2. Odontoceti = Toothed whalesa. Sperm whale

(1) Feed on squid (Sea monsters?)

(a) How does a creature that has a maximum speed of 2-4 knots and knobby teeth catch prey that swim at 10 knots?

(b) Hypothesized that they stun prey with sound blasts

Sperm Whale with Squid

Garrison, 2005, Oceanography, p. 383

16 ft Long (330 lb.) Squid Captured Off of New Zealand. The Specimen Was

Immature

Garrison, 2005, Oceanography, p. 365

a. Sperm whale (continued)

b. Hunted commercially

(a) Huge forehead contains a cavity (= MELON) containing the

SPERMACETI ORGAN

(b) SPERMACETI is a waxy high-grade oili Was used in lamps and candlesii Still used in precision machinery

(little breakdown)iii Still most numerous of the great

whales

Skull of a Sperm Whale Showing the Concave

Cavity that is Filled by the Spermaceti OrganSumich, 1992, Marine Life, p. 347

Diagram Illustrating the Melon and Spermaceti Organ of a Sperm Whale

Sumich, 1992, Marine Life, p. 348

a. Sperm whale (continued)

(3) AMBERGRISi When sperm whales consume sharp

objects, such as squid beaks, their gut produces a sticky substance that protects their digestive organs.

ii This mixture is regurgitated, reacts with seawater, and becomes rock-hard

iii Collected by beachcombers iv Refined & used in expensive perfumes to

“hold” aroma

http://www.laboratoryequipment.com/news-Researchers-Make-Perfume-Sans-Whale-Vomit-040612.aspx?et_cid=2580065&et_rid=54631806&linkid=http%3a%2f%2fwww.laboratoryequipment.com%2fnews-Researchers-Make-Perfume-Sans-Whale-Vomit-040612.aspx

Ambergris

2. Odontoceti = Toothed whales (continued)

b. Killer whale = Orcinus orca(1) Intelligent (will flip dog sled teams & seals off floating ice sheets)(2) One 24 ft. specimen contained 13

porpoises and 14 seals

2. Odontoceti = Toothed whales (continued)

c. Dolphins(1) Over 30 species including 5

freshwater(2) Elongated snout used to batter

predators such as sharks(3) Cone-shaped teeth(4) Dorsal fin curved or “hooked”(5) Make whistle noises by blowing

air out blowhole

https://en.wikipedia.org/wiki/File:NMMP_dolphin_with_locator.jpeg

c. Dolphins (continued)

(6)Atlantic bottle-nosed dolphin, Tursiops truncatus(a) Marine parks(b) US Navy uses

them to recover objects in ocean

2. Odontoceti (continued)

d. Porpoises(a) Less than 10 species(b) Relatively blunt snout(c) Flat, spade-shaped teeth(d) Triangular dorsal fin(e) Humans unable to hear noises

http://animals.nationalgeographic.com/animals/mammals/harbor-porpoise/

Harbor Porpoise, Phocoena phocoena

D. Cetaceans (continued)

3. Mysticeti = baleen whalesa. BALEEN

(1) Fibrous plates hang down from upper jawbone

Baleen Plates from a Calfornia Gray Whale

Nybakken, 2005, Marine Biology: An Ecological Approach, Fig. 3.35c, p. 134

a.BALEEN (continued)

(2) Feeding method(a) Gulp water(b) Force water out through baleen with tongue(c) Small prey retained in baleen

Nybakken, 2005, Marine Biology: An Ecological Approach, Fig. 3.35a,b, p. 134

The Feeding Process of a Baleen Whale (a) Cross-section showing feeding apparatus; (b1) Water

and plankton enter when tongue depressed; (b2) Mouth closes, tongue elevates and pushes water

out. Zooplankton retained on baleen plates

3. Mysticeti = baleen whales (continued)

b. Blue whales thought to be the largest animals that ever lived

c. Humpback whales(1) “Sing”(2)Herd schools of fish by blowing

curtains of bubbles

The whale may ... circle below the fish, blowing a ring of fizzing bubbles to act as a net, then rise up through the center... The lower jaw swings out from the upper jaw to open at a 90-degree angle, or even wider; one to three dozen grooves, or pleats, on the throat expand; and what was a sleek whale becomes a living vat swollen by as many as 15,000 gallons of water churning with fish.

... humpbacks do all this in coordinated groups... As they converge to scoop up the food, they are likely to be screaming--filling the water with prolonged, piercing shrieks that seem designed to further disorient the panicky, trapped targets.

Gentle grazers of plankton pastures? Try predators par excellence, carnivores that, depending upon how you interpret bubble netting, may qualify as makers and users of tools.

Douglas Chadwick, 1999, National Geographic, 196(1):126

Douglas Chadwick, 1999, National Geographic, 196(1):127

3. Mysticeti = baleen whales (continued)

d. California gray whale(1) Bottom feeder

(a) Lie on side and scoop up benthic mud containing invertebrates

(b) Leave feeding depressions in the benthos

(c) Observed squeezing kelp blades in mouth

Benthic Feeding Pits Are Created by the Feeding Activities of California Gray

Whales


d. California gray whale (continued)

(2) Migrate(a) Bering Sea in Arctic Circle(b)Over 100 miles/day(c) Aggregate in Scammon’s Lagoon (and

others) in Baja California (Mexico)i Mateii Calving

Annual Migration of the California Gray Whale

Lerman, 1986, Marine Biology: Environment, Diversity and Ecology, p. 272

E. Diving adaptations1. Retention of oxygen

a. High concentration of RBCs and hemoglobin

b. Myoglobin in muscles

2. BRADYCARDIA: Reduced heart rate reduces oxygen consumption

Nybakken, 2005, Marine Biology: An Ecological Approach, Fig. 3.32, p. 131

BRADYCARDIA or slowing of the heart rate exhibited by a bottle nosed dolphin during

a dive.

E. Diving adaptations (continued)

3. Why don’t marine mammals get “the bends”a. Bends is a condition that can occur in

people breathing air under pressure(1) Victim cannot straighten joints(2) First seen in underwater workers building support columns for large bridges(3) SCUBA divers

3. Why don’t marine mammals get “the bends” (continued)

b. Physiological cause(1) Nitrogen dissolves into blood faster than oxygen under pressure(2) Human blood becomes supersaturated

with nitrogen when breathing pressurized air (3) Nitrogen bubbles appear in blood if

diver ascends too quickly (Appearance of bubbles when top removed from soft drink bottle)

3. Why don’t marine mammals get “the bends” (continued)

c. Marine mammals(1) Lungs collapse when diving(2) Air (= nitrogen gas) forced away from

absorptive capillaries(3) Blood never becomes supersaturated

with nitrogen

F. Echo location1. Physics

a. Sound travels 5 times faster in water than air b. Time for echo to return reflects distance of object c. Low frequency noises used for general orientation d. High frequency noises used for high resolution


Sonogram of Echolocation Click Pulses Produced by a Sperm Whale as It Approached a Hydrophone. Note

Accelerated Pulse Rate as Distance Decreased

F. Echo location (continued)

2. Anatomya. No vocal cordsb. Sounds are generated by muscles forcing air through nasal passagesc. MELON

(1) Fatty structure in forehead(2) Focuses and directs sound

d. Echoes detected in jaw(1) Oil-filled cavities(2) Vibrations passed along to inner

ear

Cross-section of Dolphin Head Showing Structures Associated with Sound

Production



Sounds produced by air movement in nasal passages are focused by the melon. Echoes are detected in lower jaw and passed on to the inner ear

G. Behavior1. BREACHING

a. Leap from waterb. Functions?

(1) Remove itchy barnacles

(2) Warning signal(3) Playing(4) Sex display

Breaching Humpback Whale

Levinton, 2001, Marine Biology: Function, Biodiversity, Ecology, Plate XIII.4

G. Behavior (continued)

2. Stranding or beachinga. Some return to beach following removalb. Body weight will collapse lungs and organsc. Most common among pilot and sperm whales

Some of the 41 sperm whales beached in Oregon in June, 1979. None survived.


2. Stranding or beaching (continued)

d. Causes not well understood(1) Parasitic worms have been found in

inner ears of stranded cetaceans (Are they also common in unstranded animals?)

d. Causes of stranding (continued)

(2)Man-made noises(a) Navy and oil companies use sonar for

underwater exploration (b) Some stranding events have occurred

after use of sonar (Is there a cause and effect relationship or just a statistical artifact?)


3. Spyinga. Head (and eyes) raised above waterb. Thought that California gray whales use

landmarks for navigation


Killer Whales Exhibiting Spying Behavior


4. Our “friends”a. Reports of people being pushed onto shoreb. Anatomically possess a permanent smile and big eyes

Atlantic Bottlenosed Dolphin Guaranteed to look you straight in the

eye and give you a big ol’ smile

And then there is “Charlie” the tuna fish

14 Marine Mammals I.Marine Mammals A.Sea otters (Order Carnivora) 1.Insulation a.Lack blubber b.Insulated by air trapped in fur c.Vulnerable to hypothermia.

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