Animals in the Coral Reef and Their Characteristics

5 Animals in the Coral Reef and Their Characteristics Discussed

Animals in the coral reef are; coelenterates like corals, poriferans like sponges, crustaceans like shrimp, reptiles like sea turtle, and some species of fish.

The above list is better described as classes of animals in the coral reef ecosystem, as it lists major organic groups, rather than individuals. Broadly, they may further be classified as invertebrates and vertebrates.

It must also be noted that coral microorganisms like bacteria and fungi are not animals (therefore not part of the Kingdom Animalia), but belong to other taxonomic Kingdoms namely; Kingdom Monera and Kingdom Fungi [7].

This article discusses marine animals that occur in coral reef-ecosystems, and their characteristics, as follows;







-Invertebrate Animals in the Coral Reef Ecosystem

Invertebrates in the coral reef include; coelenterates, poriferans and crustaceans.



1). Coelenterates or Cnidarians (as a Class of Animals in the Coral Reef Ecosystem)

Coelenterates, which are alternatively referred to Cnidarians; include diverse invertebrates of the Kingdom Animalia, whose adaptations include a streamlined body, specialized feeding organelles, and stinging cells called cnidocytes (as well aa organelles called nematocysts), used for prey-capture and self-defense [2].

As biotic factors in the coral reef ecosystem, the coelenterates can be generally described as carnivorous aquatic organisms, whose features and behaviors place them in the role of energy-transfer between herbivores and higher carnivores in the marine ecosystem.

Coelenterates are found in coral reefs at various depths in the ocean, due to their versatility in ecologic range.

Five (5) examples of coelenterates in coral reefs are; corals, jellyfish, fire corals, sea anemones and sea pens.

Corals are the builders of reef structures, making them arguably the most prominent and important animals in the coral reef ecosystem.

They fall under the taxonomic class Anthozoa and phylum Coelenterata; and may exhibit solitary or colonial living patterns [6].

Corals build reef structures when they live colonially by secreting calcium carbonate skeletal components that are resistant to biodegradation, and continue to occur after the death and decomposition of the organism.

Reef corals can feed autotrophically through photosynthetic use of light from the Sun, along with carbon dioxide and water. This ability comes from a symbiotic relationship with Zooxanthellae; a type of algae [3].

Jellyfish, also called medusae, is a coelenterate belonging to class Scyphozoa, whose characteristics include free-swimming locomotion, stinging cells, tentacles (that bear the stinging cells) and an elongate body.

Several species of jellyfish are considered. reef animals because their navigation area usually coincides with the areal range of coral reefs.

Fire corals are a group of coelenterates of the class Hydrozoa, which have colonial living patterns [4].

The fire corals also possess stinging cells and a shallow-sea dwellers that occur within coral reef-ranges.

Unlike the colonial corals, sea anemones are mostly solitary in their living pattern/behavior, although they share several biological attributes with corals. Like jellyfish, they are equipped with tentacles.

Sea pens are yet another group of coelenterates in coral reef ecosystems. Being members of the class Anthozoa, they are recognized by their distinctive, feather-like appearance, and have sessile, minimally-locomotive lifestyles.






2). Poriferans

Poriferans are also called sponges, and include diverse organisms that add to the biological uniqueness of coral reefs with their physiological and behavioral attributes that include filter-feeding and porous outer layer [5].

The structure of poriferans is relatively simple, and include a porous external layer surrounding a central component called the spongocoel of the organism.

Details of the physiology of sponges differ significantly from one specie to another, in terms of geometry, color and size; so that some appear to have well-defined structures while others are nearly amoeboid, with multiple branches and appendages.

This is an evidence of the long history of adaptation which the group has had, as well as the ecologic resilience of its members. It enables sponges to survive in basically all zones of the reef ecosystem.

As filter-feeders, poriferans do not actively hunt for prey or forage, but rather survive by pumping seawater through their central cavity, from which they extract particles of biomass, as well as microalgae and bacteria.

The activities of poriferans help in the natural recycling of organic and inorganic resources in the ocean. This includes optimizing the efficiency of carbon, nitrogen and oxygen cycles, among others.

Because poriferans possess porous outer layers and (in some cases) complex-branching structures, they serve as habitat for some marine plants and (small) animals, which may cling to their structures for protection from currents and predators. By providing habitat to organisms, poriferans increase the species richness and biodiversity of coral reefs as a whole.

For their own protection, many sponges are able to secrete potentially toxic and deterrent chemicals that inhibit growth of competitive groups and keep predators at bay.

In spite of their ecologic resilience, sponges are susceptible to the biotic and environmental impacts of human activities and hazards, on the marine ecosystem; such as thermal pollution, plastic-related degradation, oil spill, and other forms of ocean pollution. Such events can deplete their populations significantly.

Animals in the Coral Reef Ecosystem: Poriferans use their Porous Outer Layer for Filter-Feeding (Credit: James St. John 2004, uploaded online 2020 .CC BY 2.0.)
Animals in the Coral Reef Ecosystem: Poriferans use their Porous Outer Layer for Filter-Feeding (Credit: James St. John 2004, uploaded online 2020 .CC BY 2.0.)






3). Crustaceans (as a Class of Animals in the Coral Reef Ecosystem)

Crustaceans are arthropod organisms that constitute a highly-diverse group found in all major types of aquatic ecosystems, sub-systems and micro-systems.

Some saltwater crustaceans live in various sections of the coral reef, which they modify through burrowing and sediment-accumulation, among other methods to make their environs more habitable.

The role of crustaceans in coral reefs is significant, because they occur in various sections and trophic levels of the reef, where they help with reef structural-modification, bioenergy transfer, and nutrient cycling.

In terms of physiology, crustaceans are known for their segmented bodies, jointed appendages, and rigid exoskeletons [1].

Examples of crustaceans in the coral reef are shrimps, lobsters, and some adaptive crab species.

Crustaceans are metabolically active and often bloom in population size, in ans beyond the reef system. Their feeding habits also vary widely; from predation and herbivorous consumption, to omnivorous and detrivorous, scavenging behaviors.

These habits place members of the crustacean group at various levels of the energy pyramid and food chain, with various degrees of ecologic advantage. Size disparity also causes some crustaceans to be several times larger than others, and to consume these smaller individuals as prey.

Crustaceans like some small species of crabs, may share symbiotic relationship with other reef organisms, including cnidarians like sea anemones.

Lastly, the crustaceans are an indispensable food source for several predators like fish.

Animals in the Coral Reef Ecosystem: Crustaceans may Live Symbiotically with Other Reef Organisms like Sea Anemone (Credit: Tarinth 2005 .CC BY-SA 3.0.)
Animals in the Coral Reef Ecosystem: Crustaceans may Live Symbiotically with Other Reef Organisms like Sea Anemone (Credit: Tarinth 2005 .CC BY-SA 3.0.)







-Vertebrate Animals in the Coral Reef Ecosystem

Vertebrates in the coral reef include multiple species of reptiles and fish.



4). Reptiles

The presence of some reptiles in coral reefs is evidence of the immense diversity, adaptability and resilience of this organic group.

Compared to other reef animals, reptiles are not very abundant or dominant in this habitat, but are still represented by organisms that contribute to the biological equilibrium of the reef.

Reptiles that can be found within or around coral reefs are; sea turtles, saltwater iguanas, some aquatic snakes, and water monitors. Saltwater crocodiles can also occasionally traverse the reef zone in search of small prey like fish, crustaceans, and other reptiles.

The most important and present reptiles in the coral reef are those that feed on autotrophs either as exclusive herbivores, or as omnivores. These include the marine iguanas and sea turtles that can graze on algae and seagrass, which are relatively abundant in many reefs.

In general, the size, diversity and peculiar behavior(s) of reptiles in any given coral reef-zone depends on specific constraints and conditions, which could be biological or physicochemical.






5). Fish (as a Class of Animals in the Coral Reef Ecosystem)

In coral reefs, fish represents a group of organisms that are simultaneously dominant, active, and diverse.

Various types of fish live in coral reefs. The number of species of reef fish range from hundreds to thousands.

Some of the most common fish in coral reefs include angelfish, parrotfish, butterflyfish, eels, and clownfish.

Some like parrotfish exhibit herbivorous (and occasionally omnivorous) feeding tendencies, while others are exclusively predatory.

Fish in the coral reef that are predators include some sharks, eels, barracudas and snappers.

The importance of fish to coral reefs comes from their multiple ecological roles that include regulation of algal population and mass, bioenergy transfer, biological diversification, and interactions that could be symbiotic, commensalistic, or predatory, among others.








Vertebrate and invertebrate animals in the coral reef ecosystem are;

1. Coelenterates or Cnidarians

2. Poriferans

3. Crustaceans

4. Reptiles

5. Fish






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