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Slide Show: Life on the Reef at Palmyra Atoll

What does life on an unspoiled reef look like?

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FISH EGGS

Several groups of small reef fish, such as gobies (Gobiidae), damselfish (Pomacentridae), and dottybacks (Pseudochromidae), include species that lay clutches of eggs in protected crevices. An unidentified fish laid its eggs, which have developed into embryos about 0.02 inch (0.55 millimeter) in diameter, on the underside of a settlement tile.....[ More ]

COCONUT CRAB

The coconut crab ( Birgus latro ) is the largest land invertebrate in the world. Originally distributed on islands throughout the Indo-Pacific region, the mostly nocturnal crab has been overexploited for food and extirpated on most islands inhabited by people.....[ More ]

CORAL PREDATOR

An egg cowrie snail ( Ovula ovum ), its velvety black mantle contrasting with its glossy white shell, consumes a leather coral ( Sarcophyton sp.) on a back reef at Palmyra Atoll.....[ More ]

TINY CRABS

An unidentified small crab about 0.08 inch (two millimeters) wide, possibly Liocarpilodes sp., found on the undersides of settlement tiles. Studying the tiles under a microscope, researchers sometimes find one bright, shiny compound eye looking back at them from a small hole in the surface where the crabs take refuge.....[ More ]

SEA SLUG

An undescribed nudibranch sea slug ( Eubranchus sp.) about 0.08 inch (two millimeters) long, crawls over a bryozoan colony on an experimental settlement tile. Many nudibranchs in this group tend to eat cnidarians such as hydroids, sea anemones and corals.....[ More ]

LIMPETING ALONG

The keyhole limpet ( Emarginula sp.) subsists on algae and is a relative of the snail. This specimen, just 0.18 inch (4.5 millimeters) long, cruises across a red encrusting seaweed ( Peyssonnelia sp., aka burgundy crust alga).....[ More ]

HEAVY GRAZING?

An experimental settlement tile, attached to the bottom of a back reef habitat at Palmyra Atoll. The pink coloration on the reef and the tile (sometimes called "pink paint" or "reef cement") is crustose coralline algae, which becomes especially common in places where seaweeds are heavily grazed by herbivores (such as this small school of convict tang, Acanthurus triostegus ) or limited by other extreme ecological conditions.....[ More ]

OVERCROWDING

Space on reefs is a tight commodity, even on the mostly dark undersides of corals and on small crevice walls. The undersides of settlement tiles simulate this microhabitat, just 0.4 inch (11 millimeters) wide, allowing for the examination of lethal competition among diverse plant and animal species.....[ More ]

GROWING COLONY

A young coral colony (belonging to the family Poritidae), at the three-polyp stage and 0.04 inch (0.95 millimeter) wide, grows on an experimental settlement tile amidst even smaller spiral tube worms ( Spirorbis sp.).....[ More ]

NEW COLONY

A small coral colony, composed of just three polyps some 0.05 inch (1.3 millimeters) wide, grows on top of some small polychaete worms and a sparse "turf" of a red alga, which in turn have colonized a surface of crustose coralline algae that has died and is becoming covered by a microscopic green alga.....[ More ]

NEW RECRUIT

With its short tentacles extended, a new coral recruit, just 0.025 inch (0.65 millimeters) wide, grows among a fine filigree of hydroids (a distant colonial animal relative of corals) on the border of two seaweeds, a crustose coralline alga and a burgundy crust alga ( Peyssonnelia sp.).....[ More ]

NEW POLYP

After metamorphosing into a new polyp, a young coral will start to develop its skeleton. Here, through the transparent soft tissue of the polyp, which is 0.045 inch (1.16 millimeters) wide, we see the coral's skeleton, known as the corallite.....[ More ]

METAMORPHOSIS

A recently metamorphosed coral recruit, about 0.03 inch (0.84 millimeter) wide, grows on a settlement tile. Corals, like most marine animals, have a larval stage that disperses though the water column.....[ More ]

NEW REEF

A new coral recruit, with a single polyp just 0.07 inch (1.8 millimeters) wide, has settled on the edge of an encrusting seaweed (a crustose coralline alga) overgrowing another alga ( Peyssonnelia sp.).....[ More ]

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