Fluke-Up Feeding in Hawaiian Waters

In the past few weeks our office has received numerous calls from concerned citizens about seeing a whale in distress.  The whale observed is spending long periods of time at the surface with its flukes extended above the water’s surface.  Some have conjectured that it is a whale using its tail flukes to sail; others have suggested it is attempting to cool down using its tail as a thermoregulatory device.

We believe a different hypothesis to be true.  The whale with the extended flukes is most likely a female humpback with a newborn calf. The mother is resting while still allowing her calf access to her mammary glands (located near the posterior portion of her body some 6-8 feet from her flukes).  By extending her tail into the air she is able to keep her body relatively close to the surface, allowing her to rest while minimizing dive depths for her young calf.  The calf is then able to nurse at will and expend less energy.

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FACT OF THE WEEK: False Killer Whales Call Hawaii Home

MORE ON THIS: False killer whales, while a globally distributed species, have a special tie to Maui and the four-island region. Recent research has found that a very small group of this odontocete, or toothed whale species,  calls Hawaiian waters home, making them genetically different from offshore groups. This makes this population especially interesting because false killer whales are generally thought to prefer deep ocean environments far from any land.

Genetic tests were completed on samples collected from groups of false killer whales around the main Hawaiian islands and locations throughout the North Pacific. Researchers found samples collected from individual whales close to the Islands were most genetically unique when compared to samples from whales in the Pacific Ocean, Panama and Mexico. The uniqueness of the samples indicates there are two separate populations; an inshore population and an offshore population.

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FACT OF THE WEEK: Hairy Humpback Whales

FACT OF THE WEEK: Humpback whales have hair!

MORE ON THIS: You probably know that whales and dolphins are marine mammals. Marine mammals, like terrestrial or land mammals, must have a certain set of characteristics to be called mammals – these include giving birth to live young and having hairs on their bodies. But where are the hairs on whales?

In fact, you have probably seen the hairs on humpback whales and not known what they were. The bumps on the rostrum, or head, and the pectoral fins of a humpback whale are, in fact, hair follicles. Called “tubercles,” these fist-sized bumps contain one hair follicle each, connected to a set of sensitive nerves. Why do humpback whales have these sensitive whiskers? There are multiple speculative theories in scientific literature, but no consensus.

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FACT OF THE WEEK: Bio-Fluorescent Coral Flaunts Underwater Light Show

MORE ON THIS: It is easy to see the beauty of coral reefs when snorkeling or diving during the day, but have you ever seen the colors of coral at night?

Coral reefs are known to put on a light show known as bio-fluorescence.  A family of proteins provides this fluorescence by absorbing one color and emitting another.  Each protein provides a different color; the most common is the green fluorescent protein known as GFP.  When the wavelengths of color are absorbed then re-emitted, some of the energy is lost.  This changes the wavelength, which determines the color.

Species of coral known to give off this fluorescence are found in Hawai‘i and can be seen on night dives with special dive lights.  If you’re interested in seeing this phenomenon, you can contact your local dive shop to ask about night diving to see fluorescent coral or, if you’d like to stay dry, you can visit the Maui Ocean Center which has some of this coral on exhibit.

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FACT OF THE WEEK: Hawaii’s State Mammal is Critically Endangered

MORE ON THIS: To native Hawaiians, this furry creature may be referred to as ‘llioholoikauaua, but you personally know them as Hawaiian monk seals. These monk seals are endemic, meaning they are only found in Hawai‘i. They are one of the most endangered animals in the world, with their population of about 1,100 still declining.

These marine mammals are semiaquatic, spending most of their time at sea and some of their time on land.  “Hauling out” is a process where the seal goes onto the beaches to sleep, nurse, molt and rest. Here, a mother will nurse her pup for about 6 weeks and then the roughly 200-pound pup will have to fend for itself. An adult will grow from 6 to 7.5 feet in length and will weight between 375 to 600 pounds. They are generalist feeders, feeding on what is readily available, such as squid, eel, octopi, fish, and crustaceans.

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FACT OF THE WEEK: Hawksbill turtles are nesting on Maui

MORE ON THIS: In Hawai‘i, Hawksbill turtles mostly nest on Hawai‘i Island, but Maui is home to some of the nesting beaches for ten of these turtles.  Beginning around age 20, a female will return to the area where she was born between May and October every 3 to 9 years to lay her eggs.  Hawksbills will nest at night and will lay 2-5 sets of eggs, or clutches, in the same season. Each clutch will be laid approximately 16-23 days apart.  To lay eggs, the turtle will haul out onto a beach to find a suitable area, dig a deep pit using her flippers, and then fill the pit with her eggs.  A single clutch averages 180 eggs.  Once she is done laying her eggs, she will use her flippers to fill the hole in with sand before returning to the sea.

Adult Hawksbill Turtle. Photo courtesy of Cheryl King, Hawaii Wildlife Fund.

Adult Hawksbill Turtle. Photo courtesy of Cheryl King, Hawaii Wildlife Fund.

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