Spinners live in ”fluid“ pods. With the exception of Mom and calf pairs, associations change constantly and there appears to be no real dominance hierarchy (though bigger males mate more frequently). Pod sizes average from a dozen animals to several hundred, and pods are fairly territorial (we know this because we’ve discovered genetic differences between pods that live off of the different Hawaiian Islands).
What do they eat?
Off the shores of the Hawaiian Islands, Spinners typically feed on what’s called ”the deep scattering layer“ These are small fish and invertebrates like squid that migrate vertically at night to feed on the plankton nearer the surface. A Spinner consumes about 20% of its body weight daily of these small fish and squid (or around 66,000 calories every day)!
Are Spinner dolphins an endangered species?
Thankfully no, but they are protected by the Marine Mammal Protection Act of 1972, which means we can’t ”harass“ them or alter their behavior. Though the Spinner population is difficult to count, researchers believe there are somewhere between 3500 and 5000 individuals around the Hawaiian Islands. Spinners are found worldwide from latitudes about 40 degrees north to 40 degrees south, but the world population is unknown.
Tell me some more random Spinner facts.
Spinners are mammals, so they have hair. When Spinners are born, they have hair on their rostrums (beaks), but by the time they’re adults, only the follicles remain.
The main predators for Spinners in Hawaii are Tiger Sharks and Pelagic White Tip Sharks, but Cookie Cutter Sharks frequently take quarter size pieces of flesh from the dolphins.
A Spinner can dive 800 to 1000 feet deep and hold its breath for a couple of minutes!
Spinners and other Odontocetes all have one blow hole. Mysticetes (baleen whales) have two.
Spinners can swim 30-35 mph but use the least amount of energy when they’re cruising at about 5 mph.
Based on the structure of their eyes, Spinners have great vision and can see in color.
Sources:
Norris, K., Wursig, B., Wells, R.S., Wursig, M., (1994), The Hawaiian spinner dolphin. Univ. of California Press. Berkeley and Los Angeles, California.
Welcome to the Dolphin Place: FAQ: March 2011.http://thedolphinplace.com/QandA.html#31
