Marine Mammals

Basilosaurids (marine mammals)

  Basilosaurids are a paraphyletic group of archaeocete , cetaceans known from the late middle to early late Eocene of all continents except Antarctica and South America. The family includes 11 species in 8 genera in 2 subfamilies, although some authors elevate the subfamilies to familial rank. They range in size from around 4 m […]

Beaked Whales, Overview (marine mammals)

  Beaked whales belong to the odontocete family Ziphi-idae. They are medium-sized cetaceans, with adults ranging from 3 to 13 m. They are characterized by a reduced dentition, elongate rostrum, accentuated cranial vertex, and enlarged pterygoid sinuses. There are currently 20 recognized species in five genera. They are all pelagic, living in the open oceans […]

Behavior, Overview (marine mammals)

    Marine mammalogists often divide behavioral research into categories defined by mode of study: “acoustics” is studied by recording underwater sounds with a hydrophone, “behavior” is often informally defined as that which can be seen by an observer watching animals, and “diving” is often studied by attaching tags to animals. This method-oriented view of […]

Bearded Seal (marine mammals)

    I. Description and Distribution The bearded seal is a large, arctic phocid. Adults are 2-2.5 m long and are gray-brown (Fig. 1). Weight varies markedly on an annual cycle, but an average would be 250-300 kg. Females, which are somewhat larger than males, can weigh in excess of 425 kg in the spring. […]

Biogeography (marine mammals)

    Biogeography is the study of the patterns of geographic distribution of organisms and the factors that determine those patterns. Although marine mammals are very mobile and there is an apparent lack of physical barriers in the world ocean, only the killer whale (Orcinus area), the sperm whale (Physeter macrocephalus). and perhaps some of […]

Beluga Whale (marine mammals)

  The beluga or white whale inhabits the cold waters of the Arctic and sub-Arctic (Fig. 1). Its name, a derivation of the Russian “beloye.” meaning “white,” appropriately enough captures its most distinctive feature, the pure white color of adults (Fig. 2). The evolutionary history and ecology of belugas are inextricably linked to the extreme […]

Biomagnetism (marine mammals)

  Biomagnetism is the study of the magnetic mineral, mag-1 netite, in living organisms (Kirschvink et al, 1985) and jiii is extended here to include the hypothesis that magnetite is used for magnetic field detection. The earth’s magnetic field may well be the only reliable source of navigational information in the open ocean through which […]

Bioluminescence (marine mammals)

  I. Description Bioluminescence is the ability of certain organisms to ; generate visible light as a result of a chemical reaction. Although different animals use different chemicals, these are all variants of two chemicals: the substrate is called luciferin and the enzyme is luciferase. The chemical production of light is very efficient and does […]

Blubber (marine mammals)

    Blubber, a dense vascularized layer of fat beneath the skin, is one of the most well-known and universal characteristics of marine mammals. Although it is not strictly present in polar bears (Ursus maritimus) or sea otters (Enhy-dra lutris). all cetaceans, sirenians, and pinnipeds have blubber and it may comprise up to 50% of […]

Blowing (marine mammals)

    Blow is one of the most visible behaviors of whales when they are observed at the sea surface. Whale blows represent the rapid emptying, or expiration, of whales’ lungs through their blowholes in preparation for the next inspiration. The visibility of a blow is due to a mixture of vapor and sea water […]