Sperm Whales of Galapagos

Category: Sperm Whales
Families: Kogidae & Physteridae

Three species or Sperm whales have been recorded in Galapagos. Although the sperm whales include two families and the largest and smallest species of toothed whale, their basic body plans are very similar. They have a characteristic large blunt head, low underslung jaw, and a blowhole positioned to the left of the centre of the head. Sperm whales are deep divers, capable of staying below for considerable periods of time as they hunt for squid and fish.

SPERM WHALE

Scientific Name: Physeter macrocephalus

Adult Length: 11-18 m
Blow: Single blowhole on left side of head; blow angled forward and to the left
Breaching: Frequent, most of body leaves water
Deep dive: Often arches body; usually raises dark, broad, triangular tail flukes vertically
Group size: Group size: 1-20, sometimes more

Frequent offshore

The abundance of Sperm Whales in this region made it the focus of the whaling industry in the nineteenth century, and of extensive research in recent years. The seas around Galapagos form important feeding and breeding grounds for this species. Since the late 1980s numbers have declined from a few hundred to generally 10-20 in the 1990s. The reason for this change is unknown.

Identification: The Sperm Whale is the largest toothed whale, overlapping with several rorquals in size. However, its squarish head, blow, and wrinkled skin make it very distinctive. At the surface it generally shows a low-lying, straight back. There is a small hump instead of a fin, behind which are a series of knuckles running as far as the tail.

DWARF SPERM WHALE

Scientific Name: Kogia simus

Adult Length: 2.1 - 2.8 m (6.9 - 9.1 ft)
Blow: Blowhole displaced slightly to the left; blow low and faint
Breaching: Leaps vertically
Deep dive: Tail flukes not raised
Group size: 1-10

Occasional offshore and inshore

Identification: Very similar to Pygmy Sperm Whale (see identification notes for that species below) but marginally smaller and best identified by its slightly larger dorsal fin positioned centrally on the back. Identification remains very difficult without exceptionally good views and consequently observations at sea are often recorded as Pygmy / Dwarf Sperm Whale.

PYGMY SPERM WHALE

Scientific Name: Kogia breviceps

Adult Length: 2.7 - 3.7 m (8.9 - 12.1 ft)
Blow: Blowhole displaced slightly to the left; blow low and faint
Breaching: Leaps vertically
Deep dive: Tail flukes not raised
Group size: 1-6

Rare offshore

Identification: The small size of the Pygmy Sperm Whale means that it is most likely to be mistaken for a dolphin, although its blunt, squarish head, robust body, small dorsal fin and behavior are distinctive. However, it is extremely similar to me Dwarf Sperm Whale. Both species are typically seen travelling slowly or hanging motionless at the surface and on diving, simply sink below the surface rather than rolling forward. Both are also usually shy of boats and, when disturbed, excrete a reddish-brown ink in defence. The Pygmy Sperm Whale is slightly larger but the size and position of the dorsal fin is the key feature, being smaller and positioned further than halfway along the back.