ecology Yellow clownfish perches in a fold in its host anemone. Text and photos by Steve Rosenberg Anemonefish are aptly referred to as “clownfish” because of their swimming behavior. It is interesting to note that the differ- ent varieties of clownfish exhibit very different char- acteristics. Some are shy homebodies, some can be very aggressive, and some even share their host anemones with other spe- cies. My observations of anemonefish have taken me to dive destinations all over the Indo-Pacific, including Australia, the The Clowns of the Ocean Philippines, Indonesia, — Anemonefishes of the Indo-Pacific Micronesia and Fiji. In these areas, there are a wide variety of anemonefish to life. Scuba divers from all over the this area perhaps more than any clownfishes, are always found nes that has made this species different species of anemone- observe and photograph. world are drawn to the Indo-Pacif- other species of fish, and are per- in close association with large of fish of particular interest to the fishes, which are found living with ic by the excitement and diversity haps most often the photographic sea anemones, which in turn are scientific community. some 13 different types of anemo- The entire Indo-Pacific region found beneath the surface of the subject used to stimulate an inter- found on relatively shallow coral nes. In the wild, adult clownfishes abounds in unique and beauti- ocean. However, the diminutive est in diving there. reefs. It is the symbiotic relation- Characteristics & behaviors are never found without an anem- ful varieties of vertebrate marine anemonefish are identified with In nature, anemonefishes, or ship between the fish and anemo- In all, there are approximately 27 one. They spend most of their time 56 X-RAY MAG : 84 : 2018 EDITORIAL FEATURES TRAVEL NEWS WRECKS EQUIPMENT BOOKS SCIENCE & ECOLOGY TECH EDUCATION PROFILES PHOTO & VIDEO PORTFOLIO ecology Anemonefish swimming in and around the tentacles white or light blue for each individual Such a relationship between two very dif- of the anemones, laying their eggs be- species. These fish swim with a distinctive ferent types of animals is known as sym- side the anemones and rarely venturing rising and falling tilting motion, which has biosis, or “the situation where two species far afield. When alarmed, anemonefish earned them their common nickname, of organisms live together in a union that will take shelter amongst the anemone’s “clownfish.” is beneficial or necessary to both.” It is this tentacles. These fishes develop a special A few of the most common species of fascinating relationship between fish and mucous layer over their bodies that pro- anemonefishes, which are found in the anemone that attracts the most interest. tects them from the dangerous stinging Indo-Pacific areas, are the red and black Sea anemones are members of the nematocysts that are contained in the anemonefish,Amphiprion melanopus; phylum referred to as Cnidaria or Coelen- tentacles. In exchange for this protective the orangefin anemonefish,Amphip - terata, which include a large and varied shelter, anemonefishes feed, oxygenate rion chrysopterus; the pink anemonefish, group of relatively simple, yet versatile, and remove waste material from their Amphiprion perideraion; the yellowtail marine animals, armed with microscopic host anemone. It is believed that some of clownfish,Amphiprion clarkii; and the harpoon-like stinging capsules known as these anemonefishes will also protect the ocellaris clownfish, Amphiprion ocellaris. nematocysts or stinging cells. Sea anem- anemones from natural predators such as ones possess hundreds of tentacles, and butterflyfishes. Symbiosis they can sting prey by releasing venom The anemonefishes are small brightly Except for a brief larval period, during through these tentacles. colored fishes. Their colors range from which it simply drifts among plankton in Divers who have come in contact with hues of brown, orange, pink and red the water column, anemonefishes are burning fire coral or stinging hydroids are Juvenile spinecheek anemonefish (above) have two vertical white stripes and a visible spine with one or more bars or stripes of black, rarely found without a host anemone. certainly aware that the nematocysts that extends into the middle of the forward stripe; Family of ocellaris clownfish (top left) nestle into the tentacles of their host anemone. 57 X-RAY MAG : 84 : 2018 EDITORIAL FEATURES TRAVEL NEWS WRECKS EQUIPMENT BOOKS SCIENCE & ECOLOGY TECH EDUCATION PROFILES PHOTO & VIDEO PORTFOLIO ecology Anemonefish Pink anemonefish (left) is easily recognizable by its verti- cal white lines as well as a horizontal white line; Red and Dive and Travel black anemonefish closely resemble tomato clownfish Galápagos except that their sides are mostly black (above) is the latest in a series of informative dive are discharged when stimulated by mucus covering of the fish, or adds to only one adult spawning pair of a guides by Steve the contact of other organisms. The it in some way, so that it serves as a given species. The female is usually Rosenberg. The nematocysts are especially dense on type of cloaking device for the fish. It somewhat larger than the male. 2017 NATJA the surface of the anemone’s ten- is believed that mechanical stimula- Usually, there is only one species Gold Medal tacles. The sea anemone, which is tion alone is not enough to trigger the of anemonefish inhabiting a single award-winning carnivorous, seizes and immobilizes its firing of the nematocysts, but that it anemone, although pink anemone- e-book provides prey with these stinging tentacles and has to be a combination of contact fish are occasionally observed living detailed descrip- tions of 47 of the then uses the tentacles to pass the together with a certain chemical with a variety of other anemonefish. most popular victim to its mouth. It is very interesting stimulation. Thus, the anemonefish On numerous occasions, I have ob- dive sites and that the anemonefishes flourish in this avoids being stung because the served yellowtail clownfish, Amphi- dozens of land inhospitable environment that is so anemone, chemically speaking, does prion clarkii, sharing their anemone tours throughout deadly to other fishes. not know it is there. with an adult pair of pink anemone- the archipelago. Anemonefishes, like all other fishes, fish, Amphiprion perideraion. The pink The guide also have a layer of mucus covering their Biology and breeding anemonefish are smaller and appear contains practi- cal information on travel basics and some of the fasci- skin that prevents the anemones from Anemonefish begin their lives as much less aggressive than the yel- stinging them. The mucus layer of the males and then undergo a complete lowtail clownfish. The pink anemone- nating wildlife that visitors will encounter. This electronic anemonefish is thicker and chemi- physiological change in their repro- fish tend to hide behind the anem- interactive guide has many useful features and can be used as a travel log, allowing you to add your own com- cally different than the mucus cov- ductive organs, thereby becom- one when threatened with danger, ments and notes. It contains hundreds of high resolution ering of other closely related fishes, ing females. Although the change whereas the yellowtail clownfish will images and several videos of what you will experience which do not live with an anemone. It is physiological, it is brought about aggressively protect their host anem- on land and in the sea. Available on iTunes, Google Play is believed that this covering is ac- by social signals within the family of one. This is also true of other species and Amazon. Download it today! quired by the anemonefish during its anemonefish living in a single anem- of anemonefish such as the saddle- Yellowtail clownfish, or Clark’s anemonefish, are one initial contact with its host anemone. one. Anemonefish are monogamous, back anemonefish, which will often Rosenbergebooks.com of two species of clownfish that will swim in the water Presumably, the anemone alters the with each anemone inhabited by boldly confront and nip at divers. column sometimes six feet over their host anemones 58 X-RAY MAG : 84 : 2018 EDITORIAL FEATURES TRAVEL NEWS WRECKS EQUIPMENT BOOKS SCIENCE & ECOLOGY TECH EDUCATION PROFILES PHOTO & VIDEO PORTFOLIO ecology Anemonefish The saddleback clown- fish (above) is the most aggressive clownfish toward divers; Pink anemonefish (right) tucks in close to the pro- tective tentacles of its host anemone; Tomato clownfish (left) have an oval body with a vertical white stripe just behind their eyes. for safety, and and tentacles of the anemone to both adult fish left the vicinity of the the second- get it to retract so that the nest site anemone to try to drive the divers largest adult may be exposed and cleaned. The off. male can eggs in the nest are mouthed and Once, I observed the larger fish quickly as- fanned by the adult male during the actually biting air bubbles. Even sume the role incubation period. when the divers swam away from When juvenile anemonefish reach of breeding female if something In Fiji, I recently observed a pair the anemone, the adult fish pa- maturity, they search for an unoc- happens to one of the adult pair. of orange-fin anemonefish tending trolled an area, which was much cupied anemone. If, however, some- Thus, there is always one female and to the nest site laid on the substrate larger than the actual size of the thing happens to the female, the a dominant male, and this maintains next to the host anemone. There anemone, sometimes swimming as breeding male undergoes a physi- a stable social structure among the were four fish in the one anemone: far as six to eight feet from its pro- ological sex change by becoming fish living in one anemone. two adults and two smaller juveniles.