Chapter 7 - Life history, growth, and form

Chapter 7 - Life history, growth, and form

George JC; Thewissen JGM; Von Duyke A; Breed GA; Suydam RS; Sformo TL; Person BT; Brower Jr HK

The Bowhead Whale

2021

Bering–Chukchi–Beaufort Sea bowhead whales are born at about 4.2 m in length and 1000 kg, in lead systems along the NW Alaskan coast. Bowheads in the other northern stocks are also born in ice-covered seas. Maximum body lengths (standard measure) can reach 19 m. Regarding coloration: the skin is gray on neonates and young calves, and black on yearlings and adults. The size and shape of the chin patch is variable and does not change through life. After adulthood age, the specific areas of the skin lose pigment and turn white around the eye, the peduncle, genital groove, and base of the pectoral limb. Growth is rapid from birth to age 1, followed by a 3- to 4-year growth hiatus. Following the hiatus, the increase in body length is slow to sexual maturity at ~25 years and ~13.5 m in length. The Iñupiat recognize several growth forms associated with age; these include aġvaaq (neonate), ingutuq (yearling), qairaliq (postyearling), along with several names for large adults. Allometry of the head is marked and likely associated with extreme development of the baleen rack. The head is very large in relation to body—perhaps the largest in Mammalia. The blubber is among the thickest of any cetacean (to ~38 cm). Body mass is similar to right whales of similar length; large bowheads can reach 100 metric tons or larger. Longevity can reach 200 or more years. The age of physical maturity is unclear, and adults may increase in length through life. Their ability to navigate ice-covered seas and break through ice to breathe is singular among baleen whales.

Book Chapter

NEOMED College of Medicine

Department of Anatomy & Neurobiology

Jan to Aug list 2021