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Canthigaster rostrata

Taxonomy

Kingdom Animalia

Phylum:Chordata

Class Actinopterygii (ray-finned fishes)

Order Tetraodontiformes

Family Tetraodontidae (puffer fishes)

Quick Facts

Animal Type: Fish

Diet: Omnivore

Average size: 12 cm (4.5in) maximum

Lifespan: up to 10 years

Habitat: Shallow Coral Reefs in the Caribbean

Depth Range: 1-40m (3-100 ft)

Life History and Ecology

The Caribbean sharp-nose puffer fish (Canthigaster rostrata) is a relatively small omnivorous fish that lives in the shallow waters of the Caribbean usually on coral reefs, but they are also sometimes found in sea grass beds. These fish are usually found on the back reef, reef flat, and fore reef zones of the coral reef (Anonymous). Puffer fish are so named because of their ability to inflate their bodies as a defense against predators. Puffers inflate their bodies by filling it with air or water. This causes them to appear larger and it also makes them harder for predators to swallow. Puffer fish also have poisonous flesh filled with tetrodotoxin that keeps them from being readily preyed upon (Anonymous 2009).

Physical Characteristics/ Behavior

The sharp-nose puffer fish is a relatively small football-shaped fish that has a large pointed snout, small fins toward the posterior end of the body, and a prominent tail. The sides of the fish vary in color from a pale yellow to white with bright blue spots. The edges of the tailfin have thick dark borders that distinguish the Caribbean sharp-nosed puffer from other similar species. In females their dorsal side is usually brown and in males it is usually grey (Anonymous).

The sharp-nose puffers are territorial and coexist with other sharp-nose puffers in a very complex social structure. The females will defend a small, permanent territory, and the males defend a larger territory that encompasses several of the smaller female territories. The puffers know their territory boundaries of their other neighbors. If one puffer must cross into another puffer’s territory they change to a mottled color pattern that is thought to help camouflage them from the territories owner. This color also indicates that they are no threat if they are sighted. If the puffer is caught going into another puffer’s territory it is met with aggressive displays, such as tilting the body and presenting flank. If this display does not deter the intruder the defending puffer will face its enemy head on with fins spread out to make it look bigger. If the intruder yields to the defending puffer it will display a submissive look where he belly is flattened and it will swim away. However, if the intruder persists the two fish will circle each other in an attempt to bite one another. The sharp-nose puffer’s main defense against predators is to retreat into a reef recess. However, as a last resort puffers can inflate themselves to make them more difficult swallow (Anonymous).

Sharp-nose puffers have different behaviors at certain parts of the day. For example, at dawn spawning occurs after sunrise, during the day puffers forage and defend their territories, at dusk they seek shelter for the night, and at night they rest within the reef (Anonymous 2010).

Diet

Sharp-nose puffers are omnivorous fish that search the reef for food very actively. They usually eat small crabs, shrimps, and worms. They have also been seen picking at invertebrates, algae, and sea grasses (Anonymous 2009).

Reproduction

Sharp-nose puffers reproduce sexually by laying demersal eggs and they do not undergo a sex change during their reproductive development. The male puffer will frequently visit the female puffers in their territory during the day to reinforce their bond. During breeding season these visits results in spawning that occurs during the early morning hours. If a female is ready to spawn she will search for a good substrate to lay her eggs on. She will spend time cleaning the area while the male will nudge her in encouragement. If the female attempts to leave the male often becomes very aggressive and may even bite the female. Once the nest is ready the female will lay her eggs into the nest and the male will fertilize them immediately. The eggs are then left uncared for until they hatch into plankton. Sharpnose puffers have been seen mating in the spring, but the full extent of their breeding season is unknown (Anonymous).

Lifespan and Current Status

Sharp-nose puffers have been known to live up to 10 years. These puffers are not currently on the endangered species list or even the threatened species list. This can be attributed to the fact that the puffers are poisonous and that they can puff up to avoid being eaten. Despite these two defenses against predation groupers, snappers, barracudas and eels occasionally consume the puffers (Anonymous).

Personal Interest

There are two reasons why I am so interested in this fascinating fish. It can puff itself up in the presence of a predator to keep from being swallowed and it also is very poisonous if consumed. These adaptations to keep them from being readily hunted really fascinate me. Another fact about the puffer fish is that it is considered a delicacy in the Asian countries (Not this specific species). Specially licensed chefs that know how to clean the fish without realizing the poisons into its meat prepare the fish. This meal is very expensive and might very well threaten your life. However, in Asia many people take this risk to enjoy the sweet taste of the pufferfish.

Recent Research

Most research that has been done in recent years has been dealing with the social organization and spawning of the sharp-nose puffer. There has also been some research done on why the eggs of the sharp-nose puffer are left unattended. Paul C. Sikkel of the Oregon State Wildlife and fisheries department studied these fish in the San Blas Islands, Panama. Paul concluded that females defended territories against other females and small males. From one to six female territories were included within the territories of certain large males. Haremic males visited their females and patrolled their territories throughout the day. The smaller, non-haremic males occupied territories or home ranges within or adjacent to those of haremic males or were wanderers. The spawning between a haremic male and a territorial female occurred within the female's territory. The female prepared an algal nest into which demersal eggs were deposited. There was no parental care given to the eggs (Sikkel, 1989).

Following up on this last point that no parental care was given to the eggs, experiments were also done regarding why the sharp-nose puffer’s eggs were left unattended. It was concluded that, the eggs and larvae of the sharp-nose pufferfish are unpalatable to other reef fishes. The experiments showed that they fertilized eggs and two-day-old larvae of the sharp-nose pufferfish, were unpalatable to two species of reef fishes. Unpalatability of the fertilized eggs probably explains the absence of parental care in this dermsal spawning species. These experiments were done at Lizard Island Research Station, northern Great Barrier Reef, Australia, during 1983 (Gladstone, 1983).

Summary of Research

Most of the research being done over sharp-nosed puffers deals strictly with their social structure and reproductive habits. It can be concluded that the puffers live within a strict social hierarchy and that they leave their eggs unattended because other fish simply do not want to eat them.

Literature Cited

Please note that the following references may have either been removed or relocated by the webpage owners since the time this student report was created.

Anonymous. "Caribbean Sharpnose Puffer." Home | Oceana North America. Oceana. Web. 26 May 2011.< http://na.oceana.org/en/explore/creatures/caribbean-sharpnose-puffer>.

Anonymous. "Sharpnose Puffer." AboutFishOnline.com. 2009. Web. 26 May 2011.< http://www.aboutfishonline.com/articles/sharpnose-puffer.html>.

Anonymous. "Sharpnose Puffer." Whatsthatfish.com. 2010. Web. 26 May 2011.< http://www.whatsthatfish.com/fish/sharpnose-puffer/1580>.

Gladstone, William. "The Eggs and Larvae of the Sharpnose Pufferfish Canthigaster Valentini (Pisces: Tetraodontidae) Are Unpalatable to Other Reef Fishes." Copeia 1987.1 (1987): 227-30. American Society of Ichthyologists and Herpetologists. Web. <http://www.jstor.org/stable/1446061>.

Sikkel, Paul C. "Social Organization and Spawning in the Atlantic Sharpnose Puffer,Canthigaster Rostrata (Tetraodontidae)." Environmental Biology of Fishes 27.4 (1989): 243-54. Print.

External Links

Please note that the following external links may have either been removed or relocated by the webpage owners since the time this student report was created.

http://www.aboutfishonline.com/articles/sharpnose-puffer.html

http://oceana.org/en/explore/marine-wildlife/caribbean-sharpnose-puffer

http://www.whatsthatfish.com/fish/sharpnose-puffer/1580