The Largest (Toothed) Predator on Earth
Last week I went to see the carcass of a sperm whale bull that washed ashore at Mori Point in Pacifica. I had mixed feelings about this. It’s heart breaking to see such a magnificent beast just laying there on the beach. On the other hand, it is an exciting opportunity to see a sperm whale carcass up close (or what was left of it after the necropsy).
As far as I know the cause of death is not know yet. What we know is that it looked emaciated and possibly presented signs of trauma. One likely possibility is a collision with a ship, particularly along the west coast where ship traffic is heavy around major ports like Oakland/San Francisco and L.A. Ship strikes are not the only threat. The last sperm whale carcass found in Northern California showed up in Point Reyes in 2008. The whale died due to more than 450 lb. of trash found in its stomach.
Sperm whales are the largest (toothed) predators on earth. This bull was approximately 50 ft. long and weighed over 100,000 lb. Adult males, who are about ⅓ larger and twice as heavy as females, are solitary and travel long distances in search for food. No other species of whale has males and females that are so different from each other in size and behavior.
Clearly, size matters for Sperm Whales. Bulls often have heavy scarring on their heads likely the result of fights with other males (in addition to scars caused by squid and other prey).
Photo (right): Sperm whale intestines are long and can measure about 500 ft. in lenght. On a dead specimen, the muscles relax and double in lenght to about 1,000 ft. Notice part of the the somooth and sausage-like small intestine on top and the bag-like large intestine below.
Migratory Behavior: Males vs Females
Another interesting aspect of sperm whale society is the difference in the migratory behavior of males vs females. While males travel thousands of miles to high latitudes and colder waters every year, females stay in family groups at their breeding grounds in tropical and temperate waters.
But why only males travel far to colder waters up north?
The difference in size may explain it. Due to their huge size and need for more energy, bulls travel to higher latitudes where food is more abundant and predictable during the summer- a time to stock up and put on lots of pounds for many species of whales. A 50-foot long bull needs an average of 3,500 lb. of food/day. Females, consuming less than half of that amount, can afford to stay with other family members in warmer waters and often in a relatively small area (about 600 miles wide).
The Sea of Cortez: A Sperm Whale Hotspot
One of the most important habitats and breeding grounds for sperm whales on this side of the Pacific is the Sea of Cortez in Mexico. The Gulf’s rugged seafloor topography with deep canyons and abundance of jumbo squid (the sperm whale’s favorite food) make it ideal to raise a family. Bulls, many of them traveling from feeding grounds in the Gulf of Alaska or along the California current, are also seen here during the Spring.
Sperm whales, like this bull in the Sea of Cortez, often lift their characteristic flukes high above the surface (10-15 ft.) and they can be seen for quite a distance.
Whale watching in the Sea of Cortez is an amazing experience. Sperm whales are abundant here, but that doesn’t make them any easier to find. Spotting a sperm whale is the gold medal of whale watching and it takes patience and a little luck. If you’re looking in the right direction on the horizon and a sperm whale comes to the surface, their characteristic blow and behavior are unmistakable. Their single blow hole is placed forward and to the left on their huge head (not near the center of the skull as in other whales). This means that when they come to the surface and exhale, their blow comes out of the front of the head and is tilted about 45 degrees to one side. Moreover, when they come up for air they’ll likely stay at the surface and in the same area for 10 to 15 min.
Seeing sperm whales in the wild is one of the true wonders of nature. They spend most of their lives hunting cephalopods at1,600 ft. or more below the surface. An alien, dark and cold place for humans, but a paradise for sperm whales.
I'd like to invite you to look for whales and wildlife along the Baja peninsula and the Sea of Cortez next year. If you'd like to join me, please visit the trip's web page and reserve a space at: