This 20-inch long shallow water parrotfish helps make our beautiful beaches here in Hawai‘i. They have bright white, round teeth that are all fused together in a beak that is so strong the fish can tear off chunks of live coral, grind them up to feed on the soft coral polyps and poop out the hard coral that washes up onto the beach. A healthy reef and beach has dozens of these parrotfish that also add bright color to the reef.
The adult male ponuhunuhu is bright blue or green and has a pink star-like pattern radiating from its eye. The females and juveniles are a drab grey or brown and look like a completely different fish. All of the Stareye Parrotfish are hatched out as females and some convert into males and turn blue for breeding. The entire parrotfish family are types of wrasse and most of the wrasse have this sex and color-changing ability.
Most adult parrotfish feed by themselves on top of the reef on the coral but the Stareye Parrotfish usually feeds with a larger school of surgeonfish and when a diver gets close to the school the Stareye darts into a cave under the reef and hides. This species of parrotfish can stay motionless back in a cave for a long period of time and then will come out when the divers have gone away. At night time ponuhunuhu comes into very shallow water to sleep in a crack in the reef to avoid being eaten by sharks. It is easy to take their pictures as they are bright blue and just sit there still whereas during the day they dart around so fast it is almost impossible to get a picture of one!
Marine biologists like myself do extensive coral studies to see how healthy the coral reefs are here in Hawai‘i. Part of our survey work is to count how many parrotfish there are in a 100 meter by 100-meter section of the reef. The more parrotfish we find tells us the health of the reef. We also know that a healthy coral reef with lots of parrotfish supplies the local beaches with lots of new sand which helps protect the coastline from erosion. When you see homes along the coast fall into the ocean that may be caused by people removing too many of the parrotfish off of the reef!
You can see ponuhunuhu in action in my movie “The Worlds Guide To Hawaiian Reef Fish” up on my underwater educational web page at www.underwater2web.com. We will be adding an entire 10-part Hawaiian and Pacific Ocean marine life movie series to the web soon!
Aloha from under the surf,
Source: The Garden Island