A spongivore is an animal anatomically and physiologically adapted to eating animals of the phylum Porifera, commonly called sea sponges, for the main component of its diet. As a result of their diet, spongivore animals like the hawksbill turtle have developed sharp, narrow bird-like beak that allows them to reach within crevices on the reef to obtain sponges.
The hawksbill turtle and octopus are one of the few animals known to feed primarily on sponges. It is the only known spongivorous reptile. [1] Sponges of various select species constitute up to 95% of the diets of Caribbean hawksbill turtle populations. [2]
Pomacanthus imperator , the emperor angelfish; [3] [4] Lactophrys bicaudalis , the spotted trunkfish; [5] and Stephanolepis hispidus, the planehead filefish [6] are known spongivorous coral reef fish. The rock beauty Holocanthus tricolor is also spongivorous, with sponges making up 96% of their diet. [7]
Certain species of nudibranchs are known to feed selectively on specific species of sponges. [8]
The many defenses displayed by sponges means that their spongivores need to learn skills to overcome these defenses to obtain their food. These skills allow spongivores to increase their feeding and use of sponges. Spongivores have three primary strategies for dealing with sponge defenses: choice based on colour, able to handle secondary metabolites and brain development for memory. [9]
Choice based on colour was involved based on which sponge the spongivore would choose to eat. A spongivore would bite small sample of sponges and if they were unharmed that they would continue eating that specific sponge and then move on to another sponge of the same colour. [9]
Spongivores have adapted to be able to handle the secondary metabolites that sponges have. Therefore, spongivores are able to consume a variety of sponges without getting harmed. [9]
Spongivores also have enough brain development to be able to remember the same species of sponge it has eaten in the past and will continue to eat in the future. [9]
A sponge defense is a trait that increases a sponge fitness when faced with a spongivore. This is measured relative to another sponge that lacks the defensive trait. Sponge defenses increase survival and/or reproduction (fitness) of sponges under pressure of predation from a spongivore.
The use of structural and chemical strategies found in sponges are used to deter predation. [10] One of the most common structural strategies that sponges have that prevents them from being consumed by predators is by having spicules. If a sponge contains spicules along with organic compounds, the likelihood of those sponges being consumed by spongivores decrease. [10]
Sponges have also developed aposematism to help avoid predation. Spongivores have learned four things about sponges aposematism and they are as follows:
Unfortunately, sponges that live in the deep sea are not at an advantage due to their colour because most colour in the deep sea is lost. [12]
Sponges play an important role in the benthic fauna throughout temperate, tropical and polar habitats. [13] If there is a high volume of predation it can effect bio erosion, reef creation, multiple habitats, other species and help with the nitrogen levels.
Bio erosion that occurs in the production of reef sediments and the structural component of corals are partly produced by sponges, where solid carbonate is processed into smaller fragments and fine sediments. [13] Sponges also play a role in increasing the survival of live coral on Caribbean reefs by binding fragments together and is expected to increase the rates of carbonate accretion. [13]
The coral reefs that contain higher amounts of sponges have better survival rate than the reefs with fewer sponges. Sponges can act as a stabilizer during storms as they help keep the reefs intact when presented with a strong currents. Sponges also grown between rocks and boulders, providing a more stable environment and lowering the disturbance levels. [13] Sponges also provide habitats for other organisms to live in, without them, these organisms would not have a protected habitat.
Scientists have discovered that sponges play an important role in the nitrogen cycle. There are low amounts of nitrogen found in the water around coral reefs and most of the nitrogen that is found it bound into particulate or dissolved organic matter. Before this dissolved organic matter is able to be used by other reef organisms it must undergo a series of microbial transformations. [13] The nitrogen cycle that occurs in sponges are able to cycle the nitrogen back into the water column and can be used by other organisms, especially cyanobacteria. The cyanobacteria then can then fix the atmospheric nitrogen and then the sponges can use it. [13] Therefore, if there is a high amount of spongivores present in an environment, it can affect other aspects of the environment besides sponges.
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthparts adapted to rasping or grinding. Horses and other herbivores have wide flat teeth that are adapted to grinding grass, tree bark, and other tough plant material.
Sponges, the members of the phylum Porifera, are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells.
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation and parasitoidism. It is distinct from scavenging on dead prey, though many predators also scavenge; it overlaps with herbivory, as seed predators and destructive frugivores are predators.
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.
Sea turtles, sometimes called marine turtles, are reptiles of the order Testudines and of the suborder Cryptodira. The seven existing species of sea turtles are the flatback, green, hawksbill, leatherback, loggerhead, Kemp's ridley, and olive ridley. Six of the seven sea turtle species, all but the flatback, are present in U.S. waters, and are listed as endangered and/or threatened under the Endangered Species Act. All but the flatback turtle are listed as threatened with extinction globally on the IUCN Red List of Threatened Species. The flatback turtle is found only in the waters of Australia, Papua New Guinea, and Indonesia.
Marine angelfish are perciform fish of the family Pomacanthidae. They are found on shallow reefs in the tropical Atlantic, Indian, and mostly western Pacific Oceans. The family contains seven genera and about 86 species. They should not be confused with the freshwater angelfish, tropical cichlids of the Amazon Basin.
Parrotfish are a group of fish species traditionally regarded as a family (Scaridae), but now often treated as a subfamily (Scarinae) or tribe (Scarini) of the wrasses (Labridae). With roughly 95 species, this group's largest species richness is in the Indo-Pacific. They are found in coral reefs, rocky coasts, and seagrass beds, and can play a significant role in bioerosion.
Aposematism is the advertising by an animal to potential predators that it is not worth attacking or eating. This unprofitability may consist of any defenses which make the prey difficult to kill and eat, such as toxicity, venom, foul taste or smell, sharp spines, or aggressive nature. These advertising signals may take the form of conspicuous coloration, sounds, odours, or other perceivable characteristics. Aposematic signals are beneficial for both predator and prey, since both avoid potential harm.
Alcyonacea are an order of sessile colonial cnidarians that are found throughout the oceans of the world, especially in the deep sea, polar waters, tropics and subtropics. Whilst not in a strict taxonomic sense, Alcyonacea are commonly known as soft corals. The term “soft coral” generally applies to organisms in the two orders Pennatulacea and Alcyonacea with their polyps embedded within a fleshy mass of coenenchymal tissue. Consequently, the term “gorgonian coral” is commonly handed to multiple species in the order Alcyonacea that produce a mineralized skeletal axis composed of calcite and the proteinaceous material gorgonin only and corresponds to only one of several families within the formally accepted taxon Gorgoniidae (Scleractinia). These can be found in order Malacalcyonacea (taxonomic synonyms of include : Alcyoniina, Holaxonia, Protoalcyonaria, Scleraxonia, and Stolonifera. They are sessile colonial cnidarians that are found throughout the oceans of the world, especially in the deep sea, polar waters, tropics and subtropics. Common names for subsets of this order are sea fans and sea whips; others are similar to the sea pens of related order Pennatulacea. Individual tiny polyps form colonies that are normally erect, flattened, branching, and reminiscent of a fan. Others may be whiplike, bushy, or even encrusting. A colony can be several feet high and across, but only a few inches thick. They may be brightly coloured, often purple, red, or yellow. Photosynthetic gorgonians can be successfully kept in captive aquaria.
Trophic cascades are powerful indirect interactions that can control entire ecosystems, occurring when a trophic level in a food web is suppressed. For example, a top-down cascade will occur if predators are effective enough in predation to reduce the abundance, or alter the behavior of their prey, thereby releasing the next lower trophic level from predation.
The hawksbill sea turtle is a critically endangered sea turtle belonging to the family Cheloniidae. It is the only extant species in the genus Eretmochelys. The species has a global distribution that is largely limited to tropical and subtropical marine and estuary ecosystems.
Spheciospongia vesparium, commonly known as the loggerhead sponge, is a species of sea sponge belonging to the family Clionaidae. While it is highly toxic to many fish, this sponge is eaten by certain angelfish and is known to form part of the diet of the hawksbill sea turtle.
The giant barrel sponge is the largest species of sponge found growing on Caribbean coral reefs. It is common at depths greater than 10 metres (33 ft) down to 120 metres (390 ft) and can reach a diameter of 1.8 metres. It is typically brownish-red to brownish-gray in color, with a hard or stony texture.
Chemical defense is a strategy employed by many organisms to avoid consumption by producing toxic or repellent metabolites or chemical warnings which incite defensive behavioral changes. The production of defensive chemicals occurs in plants, fungi, and bacteria, as well as invertebrate and vertebrate animals. The class of chemicals produced by organisms that are considered defensive may be considered in a strict sense to only apply to those aiding an organism in escaping herbivory or predation. However, the distinction between types of chemical interaction is subjective and defensive chemicals may also be considered to protect against reduced fitness by pests, parasites, and competitors. Repellent rather than toxic metabolites are allomones, a sub category signaling metabolites known as semiochemicals. Many chemicals used for defensive purposes are secondary metabolites derived from primary metabolites which serve a physiological purpose in the organism. Secondary metabolites produced by plants are consumed and sequestered by a variety of arthropods and, in turn, toxins found in some amphibians, snakes, and even birds can be traced back to arthropod prey. There are a variety of special cases for considering mammalian antipredatory adaptations as chemical defenses as well.
Stephanolepis cirrhifer, commonly known as the thread-sail filefish, is a species of marine fish in the family Monacanthidae. It is found in the western Pacific, in an area that ranges from northern Japan to the East China Sea, to Korea. Other common names for the fish include kawahagi (カワハギ,皮剥) (Japanese) and “쥐치” "Jwi-chi" (Korean). The fish grows to a maximum length of about 12 inches, and consumes both plant material and small marine organisms like skeleton shrimp. S. cirrhifer is host of the parasite Peniculus minuticaudae. Some minor genetic differentiation between S. cirrhifer born in the wild and those bred in a hatchery for consumer use has been shown. The fish is edible and sold commercially for culinary purposes in many Asian countries.
Stephanolepis hispidus, the planehead filefish, is a species of bony fish, a ray-finned fish in the family Monacanthidae.
Microbial symbiosis in marine animals was not discovered until 1981. In the time following, symbiotic relationships between marine invertebrates and chemoautotrophic bacteria have been found in a variety of ecosystems, ranging from shallow coastal waters to deep-sea hydrothermal vents. Symbiosis is a way for marine organisms to find creative ways to survive in a very dynamic environment. They are different in relation to how dependent the organisms are on each other or how they are associated. It is also considered a selective force behind evolution in some scientific aspects. The symbiotic relationships of organisms has the ability to change behavior, morphology and metabolic pathways. With increased recognition and research, new terminology also arises, such as holobiont, which the relationship between a host and its symbionts as one grouping. Many scientists will look at the hologenome, which is the combined genetic information of the host and its symbionts. These terms are more commonly used to describe microbial symbionts.
A corallivore is an animal that feeds on coral. Corallivores are an important group of reef organism because they can influence coral abundance, distribution, and community structure. Corallivores feed on coral using a variety of unique adaptations and strategies. Known corallivores include certain mollusks, annelids, fish, crustaceans, flatworms and echinoderms. The first recorded evidence of corallivory was presented by Charles Darwin in 1842 during his voyage on HMS Beagle in which he found coral in the stomach of two Scarus parrotfish.
Joseph Richard Pawlik is a marine biologist. He is the Frank Hawkins Kenan Distinguished Professor of Marine Biology in the Department of Biology and Marine Biology at the University of North Carolina Wilmington. He is best known for studies of sponges on Caribbean coral reefs that reveal ecological principles such as resource trade-offs, trophic cascades and indirect effects.
Dysidea etheria, commonly known as the ethereal sponge or heavenly sponge, is a species of lobate sponge within the class Demospongiae. This marine sponge is known for its light blue color and can be found in the Caribbean as well as off the coasts of Florida and Georgia. Like all other poriferans, D. etheria is capable of both sexual and asexual reproduction. The use of spicule collection as well as chemical defenses allows D. etheria to protect itself against predators such as the zebra doris and the orange knobby star. D. etheria is also known as a host species of the invasive brittle star Ophiothela mirabilis. Lastly, various molecular biology studies have utilized D. etheria to both study foreign particle transport in sponges and to isolate novel molecules.
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