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Blue sea star in the shallows. Raja Ampat, West Papua, Indonesia.
Pink-eared mantis. Dumaguete, Negros Island, Philippines.
Also among the reef’s active invertebrates are the arthropods, segmented animals whose more familiar members include insects, spiders, and centipedes. In the oceans, arthropods are equally diverse and include crustaceans such as crabs and lobsters, as well as the little-known pycnogonids, known as “sea spiders,” and horseshoe crabs. The sea spiders and horseshoe crabs are unusual and ancient branches of the group, rarely seen and minimal actors in coral reef ecology. The crustaceans, however, are a very important group, both in their free-living forms and as parasites, as we’ll learn in a later chapter. Barnacles, the familiar white mottling seen within the splash zone of the rocky shore or on the chins of whales, are nonetheless unexpected members of the crustaceans, and more recognizable as crustaceans in their larval form; as adults they remain cemented to the rock and rely on filter feeding. Shrimps, lobsters, mantis shrimps, and many types of crabs are very common on coral reefs and range in size from tiny species almost invisible to the naked eye to huge lobsters.
Pearlfish. Lembeh Strait, Sulawesi, Indonesia.
Echinoderms are the final group of dominant invertebrates and are entirely marine. They are simple and ancient animals with five main classifications: the crinoids, sea stars, brittle stars, urchins, and sea cucumbers. Among these various groups, echinoderms play a very significant role on coral reefs. Urchins furiously graze away algae; crown-of-thorns sea stars form plague proportions that can wipe out entire coral reefs; and sea cucumbers feed on the bacteria that cover sand grains. Echinoderms also provide homes for a huge array of other organisms. One of the most shocking examples is the pearlfish that lives inside the body cavity of sea cucumbers. They are a rod-like transparent fish that emerge from the cucumber’s anus at night to feed, and they pop back in during the day to hide inside the rarely predated echinoderm.
Coral reefs are composed of organisms from some of the most disparate branches from across the tree of life, all wrapped up in one ecological hodgepodge. It is due to these long-diverged branches of life that coral reefs are considered to have higher levels of diversity than tropical rain forests, with many of a reef’s organisms dating back hundreds of millions of years.
2 Michael Benton and Richard Twitchett, “How to Kill (Almost) All Life: the End Permian Extinction Event,” Trends in Ecology & Evolution 18, 7 (2003): 358–365.
3 Wolfgang Kiessling et al., “An Early Hettangian Coral Reef in Southern France: Implications for the End-Triassic Reef Crisis,” Palaios 24 (2009): 657–671.
4 George Stanley Jr. and Peter Swart, “Evolution of the Coral-Zooxanthellae Symbiosis during the Triassic: a Geochemical Approach,” Paleobiology 21, 2 (1995): 179–199.
5 C. Hearn, M. Atkinson, and J. Falter, “A Physical Derivation or Nutrient-Uptake Rates in Coral Reefs: Effects of Roughness and Waves,” Coral Reefs 20 (2001): 347–356.
6 Michael Huston, “Variation in Coral Growth Rates with Depth at Discovery Bay, Jamaica,” Coral Reefs 4 (1985): 19–25.
7 Heike Wagele and Geir Johnsen, “Observations on the Histology and Photosynthetic Performance of ‘Solar Powered’ Opisthobranchs (Mollusca, Gastropoda, Opisthobranchia) Containing Symbiotic Chloroplasts or Zooxanthellae,” Organisms, Diversity and Evolution 1 (2001): 193–210.
8 Ken Ridgway and Katy Hill, “Marine Climate Change in Australia: Impacts and Adaptation Responses,” Report Card 5 (2009).
9 T. Wernberg et al., “Impacts of Climate Change in a Global Hotspot for Temperate Marine Biodiversity and Ocean Warming,” Journal of Experimental Marine Biology and Ecology 400 (2011): 7–16.
10 K. Ridgway, “Long-Term Trend and Decadal Variability of the Southward Penetration of the East Australia Current,” Geophysical Research Letters 34, 13 (2007).
11 Craig Johnson et al., “Climate Change Cascades: Shifts in Oceanography, Species’ Ranges and Subtidal Marine Community Dynamics in Eastern Tasmania,” Journal of Experimental Marine Biology and Ecology 400 (2011): 17–32.
12 S. Ling, “Range Expansion of a Habitat-Modifying Species Leads to Loss of Taxonomic Diversity: a New and Impoverished Reef State,” Oecologia 156 (2008): 883–894.
13 J. Cortes, “Biology and Geology of Eastern Pacific Coral Reefs,” Coral Reefs 16 (Supplement 1) (1997): S39–S46.
14 Andrew Bruckner, “Galapagos Coral Reef and Coral Community Monitoring Manual,” Khaled bin Sultan Living Oceans Foundation Publication 10 (2013).
15 Anshika Singh and Narsinh Thakur, “Significance of Investigating Allelopathic Interactions of Marine Organisms in the Discovery and Development of Cytotoxic Compounds,” Chemico-Biological Interactions 243 (2016): 135–147.
16 Mauro Maida, Paul Sammarco, and John Coll, “Effects of Soft Coral on Scleractinian Coral Recruitment. I: Directional Allelopathy and Inhibition of Settlement,” Marine Ecology Progress Series 121 (1995): 191–202.
17 Mary Elliot, “Profiles of Trace Elements and Stable Isotopes Derived from Giant Long-Lived Tridacna gigas Bivalves: Potential Applications in Paleoclimate Studies,” Palaeogeography, Palaeoclimatology, Palaeoecology 280 (2009): 132–42.
18 P. Buston and M. Garcia, “An Extraordinary Life Span Estimate for the Clown Anemonefish Amphiprion percula,” Journal of Fish Biology 70 (2007): 1710–1719.
19 D. Brown et al., “American Samoa’s Island of Giants: Massive Porites Colonies at Ta’u Island,” Coral Reefs 28, 3 (2009): 735.
20 Andrew Hoey and David Bellwood, “Limited Functional Redundancy in a High Diversity System: Single Species Dominates Key Ecological Process on Coral Reefs,” Ecosystems 12 (2009): 1316–1328.
