Shedd: The World's Aquarium logo

Lesson Plans
Explorer's Guide
The Exterior of John G. Shedd Aquarium

The Explorer's Guide contains a treasure trove of aquatic science resources developed for use in K-12 classrooms. Back to Explorer's Guide.

Napoleon Wrasse Scientific Name: Cheilinus undulates
Napoleon wrasse eat a variety of toxic reef creatures, many of them with sharp spines. The poison doesn’t make it sick and the spines don’t hurt it. Its massive lips of this magnificent creature absorb the prickles of their bristly meals.

Region: Philippines

Napoleon wrasses are the largest of the wrasses having a length up to 7.5 feet (229 cm) and weighing up to 420 pounds (191 kg). The females come in drab shades of gray, red or brown. The males are a light green to aqua with squiggly pattern on the head and front of body. These fish are easy to spot on the reef, not only because of their size, but also because the adults develop a bulky bump on the forehead and have big plump lips. A pair of spiky teeth stick out of the mouth.

Different from the adults, juveniles are very pale green with long dark spots on their scales, and have diagonal dark blue lines under the eyes.

Living alone or sometimes in pairs, napoleon wrasses live on lagoon reefs and steep outer reef slopes at depths of 3 to 200 feet (1 to 60 m). Diurnal or active during the day, this wrasse can be seen roving the reef. At night, the napoleon wrasse heads home to rest in a reef cave or under a ledge. If chased after by a predator, this fish will dive into its resting place for safety.

Juveniles hide in the coral-rich areas of lagoon reefs that are dominated by branching staghorn corals.

Napoleon wrasse live in the warm parts of the Pacific Ocean, the Indian Ocean and the Red Sea.

Prey can’t hide inside the crevices from napoleon wrasse. This wrasse can jut its jaws in front of its snout, allowing the fish to pull prey out of reef holes and crevices, with a secure grip. This big fish also hunts concealed prey by biting off the things they’re hiding under like coral branches and tables, or blowing powerful jets of water out its mouth at the sand, uncovering any hidden creatures. If an escaping prey dives under a rock on the reef frantically searching for safety, the napoleon wrasse turns over the hideaway with its powerful jaws.

The humphead mainly feeds on creatures most other fish won’t touch. Besides eating clams, snails, shrimp, crabs, sea stars, brittle stars and fish, this large wrasse eats dangerous or toxic animals like sea urchins, the crown-of-thorns sea star, boxfish, and sea hares. It is believed to have the thick padded lips that act like a pin cushion, absorbing sea urchin and crown-of-thorns spines. Pharyngeal teeth or molar-like teeth in the throat help crush all the hard-shell critters this wrasse eats.

Wrasses start their lives either as a male or a female, just like any other fish. But they can also change sex. These fish are protogynous hermaphrodites, which means they can start their life as a female and then change to the male. Wrasses are born with both male and female sex organs.

After wrasses become adults, they are called initial phase males or females. Those that were born male will always remain as an initial phase male and will never have a chance to be a dominant male. Some of the adult females will change into males. These males and the remaining females are also called initial phase wrasses. But some of the larger females will become supermales. This most often happens when a supermale dies. The supermale is larger than all the other males and has distinct colors and patterns on its skin. This coloration attracts the females to the supermale. Sex change in wrasses ensures there will always be a male to reproduce with all the females.

The few supermale wrasses on the reef sport brilliant hues to attract all those females. Initial phase males are different from the supermales. When courting the females, the color of all the males will actually become brighter and more brilliant.

Terminal phase males breed with a harem or a small group of females. The supermale is territorial which means it protects a certain area and the females there too. Wrasses are pelagic spawners, which means they gather in groups in areas where the fertilized eggs will be taken by the currents. The eggs float in the epipelagic zone or the zone in the open ocean near the surface. Here the eggs hatch out and the larvae float along until they reach a certain size. After they are large enough, the young wrasses drop down and join the other reef creatures.

>A species or group of organisms that is in danger of extinction or disappearing from the face of the earth in the near future if its situation is not improved.

A species that can be found throughout its natural range but is declining in number and may become endangered in the absence of special protection efforts.

A species that is not declining in number but is of special concern because it is sensitive to pressure by particular human activities or natural events.

A species that is not declining in number and is not sensitive to pressures by human activities or natural events.

Back to top

Threats and Management
In Asia, napoleon wrasses are sought after for their meat. Restaurants and markets sold pieces of this wrasse in 1999 for $90 per pound ($200 per kg). The meat of this fish has become so expensive because it has been overfished and is a rare catch. The lips of the napoleon wrasse are considered a delicacy or treat and are highly sought after as well. This part of the fish is sold for $300 or more.

This fish is caught by divers who squirt cyanide into their reef homes. This stuns the napoleon wrasse, making it easy to capture. When the divers do this, they poison the surrounding animals—like corals. Poisoning the corals soon kills them. With no coral, the numerous fish and other animals that rely on the coral reef as a home will soon leave. Divers will also break open the reef with crowbars and crush any corals in the way of retrieving the napoleon wrasse.

Did You Know?
Although the napoleon wrasse is one of the largest reef fish, it is easily scared off. Yet, in areas where fishing is prohibited, these fish may actually become friendly with divers and snorkelers, allowing people to even touch them.

Web Sites:
NOTE: The following Web sites are not maintained by the John G. Shedd Aquarium and will open in a new browser window.


IUCN Red List:

Print Publications:
Debelius, H. 1999. Indian Ocean Reef Guide. Frankfurt, Germany: IKAN. 321p.
ISBN# 3-9317-0267-7.

Myers, R.F. 1999. Micronesian Reef Fishes. Barrigada, Guam: Coral Graphics. 216p.
ISBN# 0-9621564-4-2.

Perrine, D. 1997. Mysteries of the Sea. Lincolnwood, Illinois: Publications International, Ltd. 312p. ISBN# 0-7853-2430-5.

Back to top

Vocabulary Words

Anal fin – the fin on the belly behind the anus.

Caudal – Having to do with the end or tail of an animal. The tail fin.

Diurnal – Active during the day.

Dorsal – The back of an animal. The large fin on the back of a fish.

Epipelagic zone – The zone of the open ocean near the surface.

Extinction – An organism that has not been present on the face of the earth for over 50 years.

Harem – A group of females that mate with one male.

Hermaphrodite – Having the sexual organs of both male and female; able to produce both egg and sperm.

Initial phase – The first phase of a certain fish, like parrotfish and wrasses, after the juvenile stage. These initial phase fish are female or they may change to smaller males. The initial phase female is drab in color.

Organism – A living thing.

Overfishing – The excessive fishing or catching of aquatic (ocean or freshwater) animals to the point that the amount of animals being caught is greater than the amount of animals born. When more animals are caught than are being born, the aquatic environment is left depleted of the targeted animals.

Pelagic spawners – Fish that gather in an area in the ocean where the fertilized eggs will be taken away on the currents to drift into the open ocean.

Pharyngeal teeth – A powerful set of molar-like teeth in the throat of fish used to for grinding.

Protogynous – Starting life as a female then changing into a male.

Species – A group of organisms capable of breeding and producing fertile offspring; organisms that share the same gene pool.

Supermale – The final phase of a parrotfish or parrotfish. The female fish metamorphoses into a male and the coloring is brilliant and bright.

Territorial – An animal that lives in the same area all the time. This animal reproduces this area and fiercely defends it.

Back to top

English Español


Napoleon Wrasse
Napoleon Wrasse

©2001-2006 John G. Shedd Aquarium   Home   Contact Us   Site Map   Help   FAQ   Jobs and Volunteering   Terms of Use