Tag Archive: mammal


TAXONOMY
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetartiodactyla
Suborder: Odontoceti (toothed whales)
Family: Physeteridae
Genus/species: Physeter macrocephalus

GENERAL CHARACTERISTICS: Have large square heads, comprising almost a third of the total body length with the largest and heaviest brain of any living animal. The head of a Sperm whales contains the spermaceti organ used in echo location. It is filled with a waxy liquid called spermaceti oil. Their single blowhole is located on the left of the head rather than on the top and they have a low, bushy spout, which is projected forward and slightly to the left. Their skin is wrinkled to increase surface area for heat loss, giving them a shriveled look. Color is dark brown to bluish-black and there usually is a large hump (no fin) on the back. There are 18-28 functional teeth on each side of the lower jaws, but the upper teeth are few, weak and nonfunctional. The lower teeth fit into sockets in the upper jaw. 

Male length to 17 m (60 ft) in length, making it the largest toothed whale. Weight up to 54,431 kg (60 tons).
Female length to 12 m (37 ft), Weight to 24,494 kg (27 tons).

Photos below: Sperm whale, Initial Assessment, 2015, Pacifica       See Pacifica Sperm Whale 2015  californiadiver.com/second-dead-whale-washes-ashore-in-pa…

18639770676_ff60f26a21_k   Photo Credit Denise Greig18378411898_f5397c0b87_o   Photo Credit: Duncan Sinfield, Youtube screenshot

DISTRIBUTION/HABITAT: Found in all of the oceans of the world except the high Arctic. Primarily an inhabitant of the open ocean in offshore areas, the Sperm whale may also occasionally be seen closer to land, providing that the water is deeper than 200 m (650 ft). In California, sperm whales can be seen in waters off the continental slope from November to April.

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Photo Credit Denise Greig

DIET: Powerful sound waves are emitted from the head which can stun and perhaps kill squid, octopuses and fish including sharks and rays. They eat about 907 kg (2,200 lbs/1 ton) per day.

Note:  Surprisingly teeth aren’t used mainly for eating. Male Sperm whales appear to use their teeth mostly for fighting other males. The whale sucks prey into its mouth and gullet which is large enough to swallow a man whole. Ref. Te Papa, New Zealand museum and The Encyclopedia of Life.

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Photo Credit Denise Greig

REPRODUCTION: Mating occurs in spring and summer.After a gestation period of about 16 months, a single calf weighing up to 500 kg (1100 lbs.) is born between July and November. The calf is suckled for up to two years.
Females protect their young by adopting a defensive ‘marguerite formation’ in which the calves are surrounded by a circle of females, facing tail outwards.
Adult males lead a solitary life except for the breeding season. Female and young male sperm whales are social and sometimes are seen in pods, or groups, of up to 50 whales.

PREDATORS: Killer whales

CONSERVATION: IUCN Red List Vulnerable VU   Large-scale hunting began in 1712 in the North Atlantic, based at Nantucket in America. These whales were not widely hunted for its meat, but for ambergris and spermaceti oil. Ambergris collects around the indigestible beaks of squid in the stomach of the whale, and was highly prized for use as a fixative in the perfume industry; spermaceti was used in the production of cosmetics and candles. Recent estimates suggest a global population of 300,000 animals, down from about 1,100,000 before whaling.

Although the International Whaling Commission brought an international moratorium on whaling into force in the 1980s Japan continues to kill whales and dolphins.

Threats: Japan continues to hunt Sperm whales every year at Lamalera, Indonesia using hand harpoons. Other threats include entanglement in fishing gear and collisions with boats.

REMARKS:
P. macrocephalus dives can last two hours and can be as deep as 3000m (9800 ft) making it the deepest diving mammal.

A white Sperm whale was featured in Herman Melville’s classic novel, Moby Dick.

SPECIAL NOTE:  On April 15, 2015 biologists and researchers from the Marine Mammal Center and the California Academy of Sciences performed a necropsy on a beached sperm whale found below Mori Point in Pacifica. Because of its size the mandible is now on the Academy roof buried underneath some soil, which will allow the tissue remaining on the bone to decompose Exposure to the sun after removal from the dirt will naturally whiten the specimen which will become part of the Academy’s research collection.

Reference: Laura Wilkinson, California Academy of Sciences.

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The photo below is a mandible from beached Sperm whale jaw several years ago. It was buried then excavated for further processing and study by the California Academy of Sciences.

Sperm Whale Mandible18661069302_a1e3689d06_o

References

Te Papa, the New Zealand museum Whale to the exhibit at the California Academy of Sciences 2015

Laura Wilkinson, California Academy of Sciences.

ARKive www.arkive.org/sperm-whale/physeter-macrocephalus/

National Geographic www.flickr.com/photos/cas_docents/18639770676/in/album-72…

Marine Mammal Center  www.marinemammalcenter.org/education/marine-mammal-inform..

Monterey Bay Aquarium  www.montereybayaquarium.org/animal-guide/marine-mammals/s…

Encyclopedia of Life eol.org/pages/328547/details

Ron’s flickr https://www.flickr.com/photos/cas_docents/18639770676/in/album-72157652727235908/

Ron’s WordPress Shortlink wp.me/p1DZ4b-1wI

 

TAXONOMY
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetartiodactyla
Family: Eschrichtiidae

Genus/species: Eschrichtius robustus

GENERAL CHARACTERISTICS: This species is mottled dark to light grey and is encrusted with patches of barnacles and orange whale lice. Unlike Humpback whales, Grey whales lack a dorsal fin and instead has a series of bumps along a dorsal ridge on the final third of the back. Gray whales have small, paddle-shaped flippers, compared to the large white flippers of Humpback whales.
Length to 14 m (46 ft).
Weigh to 36,000 kg (79,300 pounds).

(see links below for live animal photos under references).

Grey Whale18204939731_f69eecb43a_k

DISTRIBUTION/HABITAT: Now found only in the North Pacific and adjacent waters. E. robustus are primarily bottom feeders and are thus restricted to shallow continental shelf waters for feeding.

DIET: The only cetacean to feed by straining the sediment on the sea floor. mainly for bottom-dwelling crustaceans but also worms and mollusks. Water, sand and mud are expelled through the baleen and food is then swallowed.
Sufficient fat reserves are stored in the feeding grounds to allow individuals to go without food during the breeding season; on return to the feeding grounds about a third of the body weight may have been lost.

REPRODUCTION: The breeding cycle last two years. Gestation takes about 13 months and the single calf is then suckled for a further seven months. The mother may have to hold the calf near the surface to help it to breathe during the first few hours after birth.

E. robustus makes the longest migration of any mammal known, each autumn and spring they pass between their Arctic summer feeding grounds and the mating and calving lagoons in Baja California.
Round-trip up to 20,400 kilometres (12,676 miles).

LONGEVITY: 25 to 80 years.

PREDATION: The only non-human predator of Gray whales is the Killer whale with up to 18% of all Gray whales showing evidence of an Orca attack.

CONSERVATION: IUCN RED LIST Least Concern (LC)
The Eastern North Pacific population has made a significant recovery since 1947 when whaling stopped for this species and now they number between 19,000 – 23,000, which may be close to their original population size.
Three gray whale breeding lagoons in Mexico enjoy some protection in the form of limitations on boating, fishing and coastal development.

Threats: Collisions with ships, entanglement in fishing nets and pollution. Habitat degradation resulting from drilling and dredging is also a problem.

REMARKS: The California Academy’s Gray whale was a juvenile that beached in Baja California in 1966. It would have been about 35 feet long while alive. The two small, hanging, isolated bones towards the tail are remnants of pelvic bones, evidence that whales descended from four-legged land mammals that returned to the ocean about 53 million years ago.

References

California Academy of Sciences Docent program Whale  information March 2015

IUCN Red List www.iucnredlist.org/details/8097/0

ARKive  www.arkive.org/gray-whale/eschrichtius-robustus/

Ron’s flickr link www.flickr.com/photos/cas_docents/18204939731/in/album-72…

Shirihai, H & Jarrett (2006) Whales Dolphins and Other Marine Mammals of the World Princeton University Press.

Evans, P & Weinrich, M (2002) Whales Dolphins and Porpoises D K London New York Munich Melbourne and Delhi.

Reeves, R, R, et al (2002) Guide to Marine Mammals of the World  Chanticleer Press, Inc.

Ron’s WordPress Shortlink https://fishoncomputer.wordpress.com/wp-admin/post.php?post=5851&action=edit

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