Longnose Butterflyfish

Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciforms
Family: Chaetodontidae
Genus: Forcipiger
Species: Forcipiger longirostris

Butterflyfish, like butterflies, come in all shapes, sizes and colors. Today, I’m going to introduce you to the longnose butterflyfish, or Forcipiger longirotris.

Longnose butterflyfish are distributed throughout the Indo-Pacific Ocean, including around the islands of Oahu and Maui of the Hawaiian island chain. These fish are found on the very edges of seaward reefs, or coral reefs that extend toward the sea.

When you look at the genus name Forcipiger, does anything pop-out at you? Forcip-iger

Forceps are pincer-like instruments made for grasping and holding objects, similar to tweezers. Forceps are typically used in medical and surgical situations.

Forcipiger refers to how the organism feeds, grasping and eating prey whole. The species name longirotris describes the fish’s long snout. F. longirotris feed on small crustaceans found in the rocky crevices of the reef, or they suck them right off of branching coral.

Most individuals of this species are bright yellow with a black head, and a long, thin, silvery-white snout. Rare individuals have been recorded as all black or brown instead of yellow, though this color change has never been recorded in an aquarium. All longnose butterflyfish have a clear caudal (tail) fin, but the rest of their fins are yellow. Near the base of its tail fin is a black spot called an eyespot.

A defense tactic, eyespots are spots on an organism that resemble eyes to confuse predators. Eyespots are typically located away from the head and anything vital. For fish, it’s to fool predators into thinking that the tail end of the fish is the head, especially since the eyes of F. longirotris are hidden in the black coloring of its head. For insects, these eyespots can look like the eyes of other organisms. Eyespots are a common defense found on fish, reptiles, and insects, and each group uses them differently.

Longnose butterfly fish have often been observed in pairs. These fish form monogamous pairs during the breeding season, though it’s unclear if the same two would pair up in the next breeding season. The female releases thousands of eggs into the water column to be carried elsewhere in the water current.

I’ve swum around reefs in the Pacific Ocean twice, once in Hawai’i and once off the Great Barrier Reef. Both times were snorkel only, so I didn’t explore too deep around the reefs, and I doubt I would have seen these fish. I hope to fix that someday because these guys look impressive with their long noses!
There is potential research for Forcipiger longirotris. One, there’s no clear explanation as to why some individuals change their color to all-black or brown and why it’s never done in an aquarium setting. Two, they are labeled as Least Concern by IUCN Red List, but their population numbers haven’t been evaluated since 2009, so there is potential research in re-evaluating their population numbers.

Sources and links:
https://fishesofaustralia.net.au/home/species/425#moreinfo
https://www.waikikiaquarium.org/experience/animal-guide/fishes/butterflyfishes/longnose-butterflyfish/
https://www.fishbase.se/summary/Forcipiger-longirostris.html
https://www.iucnredlist.org/species/165667/6085300

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