A Better Understanding of Coral Reef Ecosystems

Pelagic predators such as these barracuda, Sphyraena qenie, are part of the coral reef ecosystem in the U.S. Line Islands (NOAA Photo by Kevin Lino).
A team of scientists have embarked from Hawai'i on a three-month survey of coral reef ecosystems at Johnston Atoll, the U.S. Phoenix Islands, the islands of American Samoa, and the U.S. Line Islands in the tropical Pacific Ocean. The overarching objective is to better understand the coral reef ecosystems of these areas, many of which are seldom explored. The research expedition is part of a regular monitoring program, conducted by the Coral Reef Ecosystem Division (CRED), headquartered in Honolulu, Hawai'i. The expedition is supported by NOAA's Coral Reef Conservation Program and involves extensive cooperation among NOAA scientists and research partners, including the University of Hawaii Joint Institute for Marine and Atmospheric Research (JIMAR), the U.S. Fish and Wildlife Service, San Diego State University, and the Papahānaumaokuākea Marine National Monument.

The research expedition will be carried out from February 27 to May 24, 2012 aboard the NOAA ship Hi'ialakai. Under the leadership of Chief Scientists Dr. Jill Zamzow, Dr. Bernardo Vargas-Angél, and Jamison Gove, a diverse team of researchers will be conducting multidisciplinary coral reef ecosystem surveys, assessing the status of fishes, corals, algae, marine invertebrates, and the oceanographic conditions in which these organisms exist. The scientific data collected during the three-month research expedition will enable informed and effective implementation of ecosystem-based management and conservation strategies for coral reef ecosystems, helping to ensure their protection for generations to come.

Monday, April 20, 2009

Small but Colorful

photo by Cristi Richards

A nudibranch (Chromodoris elisabethina) crawling along the reef

While many of the animals that people think of when someone mentions coral reefs are large or conspicuous like turtles, fish, and even the coral itself, other residents of the reef are small and easily missed. One such creature is the nudibranch.  Nudibranch literally means 'Naked Gills' which is appropriate because it breathes through a set of bushy external appendages on its back, sort of like wearing your lungs on your back. Nudibranchs, also sometimes called sea slugs, are a group of shell-less snails that live in all oceans of the world and at almost every depth. They are often very colorful but are easily overlooked because they are usually less than an inch long. They tend to be carnivorous, feeding on sponges, anemones, or other sea slugs and the 'horns' that you see at the front are actually sensory organs used for touch, taste and smell. They defend themselves either by blending into the algae or coral around them or by using bright colors to indicate that they are poisonous.  If you look closely, you may be lucky enough to spy one crawling along the reef.


  1. Aloha NOAA CRED Team,

    Thanks for all of your hard work on this blog I want you to know that you are making a difference in the student's lives, they love seeing what you are up to every week and get such excitement when answers to their questions come back from the ship.

    We have a lot of questions concerning the Nudibranch:

    Per 2 - Are there any dangers in having the gills located on the back of the Nudibranch? What is the normal lifespan of a Nudibranch?

    Per 3/6 - Are the Nudibranch actually poisonous or do they just use the bright colors to make it seem like they are poisonous? How do the Nudibranch catch and eat their pray. Do the Nudibranch change colors such as a chameleon to blend into their surroundings or do they just come in a variety of different colors?

  2. Great questions! To answer them I asked one of our invertebrate experts Molly Timmers. Here's what she says:

    Nudibranchs are actually quite toxic and therefore have few predators. Thus, there are not many dangers to having the gills located on their back. However, not all nudibranchs have their gills located on their backs. Some have them located within their mantel and others within protrusions along the body called cerata. These cerata not only contain their gills but also stinging nematocysts which are derived from their diet.

    The lifespan of most nudibranchs is less than one year.

    Nudibranchs are not toxic to humans, but they are poisonous to most creatures underwater. Their brilliant colors serve as warning signs to predators indicating that they don't taste good.

    Nudibranchs are quite the carnivores. They eat sponges, bryozoans, hydroids, corals, and even other nudibranchs. They have sensory organs called rhinophores that protrude like a pair of horns on their head. The rhinophores help to detect prey and guide the nudibranch in the right direction for its next meal. Some nudibranchs will swallow their prey whole, others use jaws, but all of them have a radula which is a tongue lined with teeth - think of a saw. This radula moves back and forth enabling the nudibranch to eat it's prey.

    Unlike a chameleon, although coloration can differ slightly between individuals within a given species, a nudibranch's colors are permanent.