Great Barrier Reef Ecosystems Project by Clio Sun on Prezi
relationship is predicted between the abundance of predators and the among reefs between predator abundance and maximum prey-species richness. In the Great Barrier Reef there are Predator and Prey. A predator and prey example in the Great Barrier Reef is sharks and fish, where the shark is the predator. Sublethal or nonlethal predator-prey interactions (predation risk) can influence prey species' behaviours and . Trade-offs between foraging and hiding in coral reef fish prey: 47 .. The qualitative relationship between light levels and.
Thus they are called "primary producers. One important algal group, benthic bottom-dwelling algae, rapidly grows over dead coral and other inert objects, providing a grazing yard for herbivores, such as parrotfish.
Their gentle disposition disappears, however, in the presence of another favorite food: When feeding, the butterflyfish turn into vicious predators, darting in to rip off the anemones' fleshy tentacles.
Having evolved resistance to the anemones' toxins, they need only get past clownfish guards to pick off a delicious meal. Packed with miniature toxin-loaded harpoons nematocyststhe tentacles of sea anemones provide an excellent deterrent against almost all would-be predators. Saddled butterflyfish, though, have evolved resistance to the toxins and apparently relish the tentacles. Still, to grab a meal, the butterflyfish must get past the anemones' second line of defense: One such predator, the smallscale scorpionfish Scorpaenopsis oxycephalaclosely resembles the reef's rocky, algae- and coral-encrusted bottom, where it lies in wait for crustaceans and small fish, such as gobies.
Safely tucked in coral crevices or half-buried in sand and rubble, gobies Gobiidae family maintain a low profile on the reef to avoid predation. In addition, they have evolved independently swiveling eyes that constantly search the water for potential attackers. But their efforts can be foiled by ambush predators, like the smallscale scorpionfish, whose camouflage prevents gobies and other prey from seeing them until it's too late.
Evolution: Survival: Coral Reef Connections
The two fish benefit by the association; a third fish, however, has evolved to take advantage of them both. Using a devious disguise and copycat behaviors to attract larger fish, the fanged ambush predator, called a fangblenny, rips living tissue from surprised prey.
In the world of predators and prey, the normal rule is that big creatures eat smaller creatures. But sometimes the tables are turned, as in the case of the bluestriped fangblenny Plagiotremus rhinorhyncosa small but sinister predatory fish. Evolved to perfectly mimic the bluestreak cleaner wrasse, the fangblenny falsely advertises cleaning services to larger fish, such as the reef lizardfish.
Once the bigger fish moves in close, the fangblenny attacks and darts away with a mouthful of sushi. With beautiful, ornately designed shells, coneshells are highly sought-after by shell collectors. These gastropods have evolved as deadly predators, however; a single puncture from their venomous radula modified tooth can rapidly paralyze and even kill a human. Of course, coneshells evolved not to defend themselves against collectors, but to efficiently kill prey, such as the blueband goby.
Gobies are the most diverse fish family on the reef, with more than species described. With their generally small sizes and ability to adapt to a wide variety of specialized habitats, gobies have become the most diverse marine fish family in the world.
This does not mean they are always successful at avoiding predators, though.
For instance, the blueband goby Valenciennia strigata is eaten by a variety of predators, including the venomous coneshell. Noisily chattering as they work, mating pairs build nests of guano-cemented leaves and grasses in fig trees. But even in the shelter of the trees, chicks and eggs are often stolen and eaten by marauding silver gulls.
The common silver gull Larus novaehollandiaelike most gulls, will eat just about anything it can get its heavy, hooked bill into. Often scavenging recently dead animals and even trash, silver gulls help keep shore areas clear of debris. But once the debris is gone, they turn to other easy pickings: While seabirds hunt far out beyond the reef, reef herons fish along the cay and reef flat.
They have evolved to hunt during low tide, allowing them to wade the shallows. With excellent eyesight and marksman-like aim, they expertly spear fish fry, adult fish, and crustacean prey from beneath the water's surface. Silvery schools of many species of juvenile fish called fish fry find some refuge from the intense predation of outer reef zones by living near the shoreline. But they can't let down their guard completely. While feeding on benthic algae and floating microscopic communities of plants and animals, they are easily visible from above the water's surface and often fall prey to hunting reef herons.
The winners will pass on their genes -- and, thus, their winning traits -- to their offspring, while the losers' genes will disappear. Thus, each successive generation faces stiffer competition than the last, as individual competitors become better and better adapted "fit" to their environments.
Read about different competitive relationships on the reef. The bottlenose dolphin Tursiops truncatus and other toothed whales are solitary predators who remotely detect prey by echolocation. Emitting a series of clicks and whistles, the dolphin then waits to analyze returning echoes.
Echolocation is so precise that a dolphin can determine the size, direction, and distance of a school of prey fish, and even sizes of individual fish in the school. To feed, dolphins use a fast, surprise attack, and, unlike the hunting packs of trevallies, dolphins can successfully hunt alone.
Bigeye trevallies Caranx sexfasciatus prey on schools of small fish using a very different approach than do bottlenose dolphins.
Ecological Relationships - Coral Reefs
These trevallies have evolved to cooperate with each other, much like wolves in a pack, to surround, corner, confuse, and finally kill their prey. A single trevally would have a very difficult time attacking a school of prey fish, with its hundreds of pairs of watchful eyes and ability to move as a unit to avoid predators, so each trevally benefits from participating in the hunting party.
Male Spanish dancers Hexabranchus sanguineus essentially enter dance competitions to win their mates. The judge is the desired female, who decides which writhing, scarlet red male wins the right to father her offspring.
This process is an example of "sexual selection," in which a male "wows" a female into mating with him. Often, as in the case of Spanish dancers, the male risks his life to put on a winning show, since his mating behavior makes him more conspicuous to predators. Fortunately, Spanish dancers possess a potent toxin, which deters predators. Sea sponges and other sessile anchored organisms compete fiercely with each other for space using physical and chemical warfare. Over millions of years of turf wars, sponges that evolved anti-sponge toxins, like the Microcionidae, were often victorious over non-toxic varieties.
Thus, most sponges living today produce potent toxins, which provide a secondary benefit of discouraging all but the most highly adapted predators, such as the sea slugs.
Competition for a common resource can exert pressure on a species to alter not only their physical form, but also their behavior. For instance, neither parrotfish Scarus spp. Instead, they avoid predation by different adaptive behaviors. Parrotfish graze among schools of venomous, spined rabbitfish, which are seldom attacked by predators. Long-nosed butterflyfish Forcipiger flavissimuslike their parrotfish rivals, are not physically well protected against predators.
Instead, both species have evolved behaviors that help them avoid being eaten while they graze for benthic algae. Butterflyfish typically swim in pairs near a particular clump of coral. If threatened, they expertly wedge themselves between coral branches and erect fin spines so they are almost impossible to dislodge.
Saddled butterflyfish Chaetodon ephippium mainly subsist on a diet of benthic algae; but they have also developed a taste for meat, and will rip tentacles from sea anemones if given the chance.