Strap-toothed Whale

Fascinating facts about the Strap-toothed Whale

• When John Edward Gray named the species in 1865, he honored museum curator Edgar Leopold Layard, whose sketches of a skull first revealed the whale’s bizarre, arching lower-jaw teeth that can reach 34 cm and lock the mouth shut. This bizarre lock limits adult males to opening their jaws just 3–4 cm wide, a physical constraint that likely fuels fierce tooth-based contests for mates.
• At up to 6.2 m long and 1,300 kg, the strap-toothed whale is one of the largest Mesoplodon species, and newborn calves may be up to 2.8 m long.
• A lone male was found dead off Myanmar at 16° N in 2011, more than 5,000 km north of any previous record, showing the species can occur far beyond its previously accepted sub-Antarctic range.
• These whales can plunge nearly two miles (3.2 km) deep, but most dives hover around half a mile (800 m) for 10–15 minutes, using powerful echolocation clicks and whistles that travel through water layers over 1,000 m deep to locate squids like the vampire squid living 600–900 m below the surface.
• Predators such as killer whales have been observed hunting solitary strap-toothed whales, a reminder that even a deep-diving, stealthy beaked whale faces top-level threats, underscoring the fragile balance of life in the ocean’s dark zones.

At a glance

About the Strap-toothed Whale

The strap-toothed whale (Mesoplodon layardii) is a strikingly patterned beaked cetacean, easily recognized by its white beak, dark facial mask and a pale "cape" that runs halfway between the dorsal fin and the head. A white-tipped dorsal fin and flukes complete the contrast, while a subtle neckband separates the darker grey of the head and melon from the rest of the body. Adult males bear a pair of massive, 34 cm curved teeth that arch over the upper jaw, limiting their gape to just a few centimeters, whereas females and juveniles lack functional teeth and retain a more conventional mouth opening. Growing to about 6.2 m (20 ft) and weighing up to 1,300 kg (2,900 lb), these whales inhabit the deep, cold waters of the Southern Ocean, with a circumpolar distribution that includes sub-Antarctic and temperate zones around Tierra del Fuego, the Falkland Islands, Western and Southern Australia, New Zealand and occasional far-north strandings as far as Brazil and Myanmar. Their life below the waves is guided by sophisticated echolocation clicks, low-frequency grunts and high-pitched whistles that pierce the darkness of depths often exceeding a kilometre. Primarily squid hunters, they consume oceanic cephalopods such as Vampyroteuthis infernalis, Histioteuthis spp., and Gonatus antarcticus, with males and females targeting similarly sized prey despite the male’s restricted jaw. Often seen in small groups of two to ten, they surface beak-first at steep angles, sometimes basking calmly before slipping away, and can dive for up to fifteen minutes, plunging to half-mile depths for hours at a time. Their occasional “porpoising” and rare breeches hint at a hidden agility beneath the surface, a surprising trait for a whale whose massive tusks suggest a more cumbersome existence.

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