The Anatomy and Physiology of Toothed and Baleen Whales Brunilda Cruz

Like all mammals…  Whales breathe air into lungs.  They have hair.  Whales are warm-blooded.  Whales have mammary glands with which they nourish their young.  Whales have a four-chambered heart.

Toothed Whale (Killer Whale)

 Counter shading allows the Orca to blend into the ocean environment and camouflage itself from prey.  Color differences may also help orcas identify the opposite sex since females have an oval genital patch with three black spots and males have an elongated white patch with a single black slit covering the penis.

Reproduction  In the wild, orcas become sexually mature between the ages of 10 and 18 years of age and are thought to be actively reproducing by the time the male reaches about 20 feet in length and the female reaches about 16 feet.  At birth, a calf is generally about 6-7 feet long and weighs around 400 pounds.

Male or Female?  The male’s dorsal fin is upright and up to six feet taller than the female’s dorsal fin.  The female dorsal fin goes up to 4 feet tall.

Teeth  Orcas have pairs of large sharp teeth distributed on each side of the jaw, for a total of 40 to 56 pairs.  The teeth curve inwards and backwards - this helps the orca catch its prey.  Teeth average about 3 inches long and about 1 inch in diameter, but some are even longer.  An average-sized orca will eat about 550 pounds of food a day.

Spouting-Breathing  Orcas breathe air at the surface of the water through a single blowhole located near the top of the head. Their blow is a single, low bushy cloud.  They take 4 short breaths 10 to 30 seconds apart and then dive for between 1 and 4 minutes.

 The Orca's circulatory system utilizes many arteries and veins in the flippers, flukes and dorsal fin that allow it to transfer heat from the body in warm conditions or conserve heat it as it swims in icy seas.  Its size also helps conserve heat as its surface area to volume ratio is lower than other mammals.  A high metabolic rate increases heat production while a coating of blubber reduces heat loss, streamlines its body to conserve energy and serves as food storage.

Whale Flukes  A Whale's tail is composed of two lobes, each of which is called a fluke. There is a notch, a v-shaped indentation where the flukes (or lobes) of a Whale's tail meet.  Flukes move up and down to propel the Whale through the water.  Flukes have no bones in them. They are made of muscles and dense fibrous tissue.  The arteries that supply the flukes with blood are surrounded by veins to maintain the Whale's temperature.  The Blue Whale's flukes are the largest and are 25 feet wide.

Photos of Whale Flukes

 The heartbeat of a Whale varies from Whale to Whale. Like all larger animals, they have a slower heart rate than smaller animals.  The average heart rate of large Whales is from about 10 to 30 heart beats per minute.  The heart rate of the beluga was measured at beats per minute.  Whales lower their heart rate when they dive beneath the water, this conserves oxygen and lets them dive longer.

Right Whale

Baleen Whales (Right Whales)  The Right Whales head is approximately 1/3 rd of its body’s length.  one skull of a Baleen Whale was measured at 5.2 meters and weighed 2,200 pounds.  The jaw in this head is greatly arched, allowing the right whale to carry extremely long baleen plates, up to 9 feet long. About plates are found on each side of the mouth with a clear opening in the front.

 The Right Whales skeleton is simple and compared to other whales it is light.  The skeleton accounts for only about 14-15% of the whale's total body weight.  The Whale's spine consists of vertebrae including 7 cervical, fused in the neck region apparently to hold the enormous head, thoracic, lumbar, and 25 caudal.  In comparison humans have 33 vertebrae -- 7 cervical, 12 dorsal, 5 lumbar, 5 sacral, and 4 coccygeal.  Almost all mammals have seven cervical (or neck) vertebrae no matter how long the neck.

Photo of Right Whale Skeleton

 Right whales have pairs of ribs while humans have 12 pairs.  There arm bones (humerus, radius and ulna) in the right whale are extremely short compared to human proportions  The pelvic region in the whale is reduced to an elongated pelvic bone.

 The flipper of the Right Whale is similar to a human hand.  The Right Whale’s tail muscle’s are the largest part of its body.

Right Whale Skin  Right Whale’s have very thin skin.  Their skin can be rubbed off very easily.  Researchers have observed numerous white marks on right whales.  The skin covers a thick layer of blubber, strong muscles, and a lightweight skeleton.

 Skin flaps on the dorsal (bottom) side of the whale cover its genitalia (two nipples and birth canal in the female and a retracted penis in the male). The whale's genital slit is located further back along the central dorsal line from the navel but before the anus.

Blubber  The first purpose of the blubber is that it is used as a barrier, to maintain the warmth inside the whale and prevent heat loss to the cold ocean water.  Second, the blubber serves as a food reservoir, this is especially important when the whales cannot find large patches of zooplankton in northern waters or when female Right Whales are pregnant, they move to warm southern waters.  Third, Blubber is used as fairing material.

Digestive System  Scientists believe that Right Whale’s have three major chambers in the stomach, possibly four, the fourth being an extension of the intestine.  Food passes through the whales mouth into its esophagus, on its way to the whale's multi- chambered stomach.  It then passes through the intestine and the remaining waste eliminates into the ocean.

 The first chamber in all whales is a dilatable, sac-like, extension of the esophagus with no digestive glands.  The second chamber is where digestive juices are released, pepsin and hydrochloric acid have been found in parts of the stomach of some whales.  Most Whales have a third chamber, which is the pyloric part of the stomach.

Kidneys  Like human’s the Right Whale uses its kidneys for cleaning the blood and separating out the waste products for later removal from the body.  Eliminating waste products brought in by the kidney requires a certain amount of water.  Not only is water necessary for the production of urine, but for feces, oxygen extraction in the lungs, and in most mammals for sweating (temperature regulation).

How they intake water  Scientists believe these animals do not drink seawater, but satisfy their need for water with the fluids contained in their diets.  Plankton-eaters, such as right whales, must produce a urine that is more concentrated than seawater in order to accommodate their diet and any incidentally swallowed seawater.

 Whales lose additional water when they nurse their young.  One solution is the concentrated milk (30-40% fat) as compared to cow's milk (4% fat).  This type of milk is not just needed for fast growth of the baby, but to economize on the mother's fluid levels.  A more watery milk would dehydrate the mother who cannot easily feed with a newborn by her side.

Spout-Breathing  A Right Whale has a distinctive V-shape blow.  Most of their time is spent underwater.  most right whales average 5 to 10 breaths at intervals of 15 to 30 seconds before diving for 5 to 30 minutes. Most deep dives are about 20 minutes.

Genitalia  Right whales exhibit similar reproductive organs as other mammals, with some distinctive differences.  The female's mammary nipples are hidden within skin slits on either side of her body just forward of the genital slit. The umbilicus (belly button) is forward on this ventral line. The anus is located closer to the tail stem.  In males, the penis is coiled within the body cavity. The erect penis may reach a length of 10 to 11 feet. A male's testes may weigh up to a ton or more.

Reproduction  Nobody has ever witnessed a large whale giving birth, scientists estimated the gestation period to be between 350 and 400 days.  Calving takes place during the winter off the coasts of Georgia and northern Florida.  The calves are four to five meters long at birth and weigh approximately 1760 pounds. The mother nurses the calf for 10 to 12 months during which the calf grows to between 8 and 10 meters and pounds.

 Calving intervals are three to five years, which includes a one year lactation period and a one year gestation period.  Males don't participate at all in raising the calf.  Researchers have rarely spotted males in the calving grounds off the southeast coast, and the only times males and females interact is during sexual behavior.

Mating

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