oceanography (test 2)

• a coelenteron is a single body cavity for both the ingestion of food and release of digested waste
• nematocysts are stinging cells typically abundant of the surface of the tentacles that the coral can eject into the prey
• mesenteries secrete enzymes within the digestive cavity of the coral to chemically digest the coral's food
• order scleractinians: stony hard corals
• hard corals are the primary building blocks of coral reefs
• hard corals secrete a basal skeleton of calcium carbonate as the mineral aragonite
• octocorals include some hard and soft corals and also gorgonians or horny corals
• octocorals get their structure and body support from calcium carbonate spicules that are deposited within their body walls
• corals reproduce predominately sexually (sexual reproduction increases genetic diversity)
• most corals are hermaphrodites (produce both male and female gametes)
• spawning: egg and sperm released into water column simultaneously
• brooding: spawned sperm fertilises eggs within the polyps, larvae is then released into the water column when relatively well developed
• budding: young coral grows out from adult coral
• parthenogenesis: embryo grows without fertilisation
• coral bail-out: a single coral polyp splits from an adult polyp before drifting and settling elsewhere, as the new polyp grows it begins to form body parts
• asexual reproduction results in genetically identical offspring
• primary productivity: amount of organic matter fixed in an ecosystem as a result of photosynthesis
• biomass: renewable organic matter from plants and animals
• coral reefs are characterised by a low biomass of benthic algae (allowing for rapid growth of light-dependent corals)
• zooxanthellae are symbionts that perform photosynthesis and supply their host with nutrients
• the high primary productivity of coral reefs is due to the presence of zooxanthellae, which live within the tissues of corals and other cnidarians
• algal turfs are complex assemblages of fast colonising and growing algae
• grazing organisms monitor algae populations
• grazing organisms include: parrotfish, surgeonfish, rabbitfish, damselfish and blennies
• parrotfish have strong fused teeth that can break coral and throat teeth that grind the limestone, exposing plant tissue from within
• some grazers have comb-like teeth that can scrape algae and detritus from the seabed
• Browsers are herbivores that remove parts of algae that are rich in nutrients, low in toxins or are structurally weak (include rabbitfish and drummer)
• Detritivours consume dead plant material and target the nutrient-rich coating that surround dead plant fragments (including blenny)
• carnivores control populations of grazers that can damage the reef and assist in nutrient cycling in the ecosystem (include planktivours, benthic predators and piscivores)
• plankton: organisms that are unable to control their movement against currents
• plankton is derived from the greek word planlktos, meaning wanderer or drifter
• plankton's horizontal position is primarily determined by currents in the body of water they inhabit
• nekton organisms: organisms that can swim against the ambient flow of the water environment and control their position
• holoplankton: spend their entire life cycle in the planktonic stage (e.g. alage, copepods, salps, some jellyfish and krill)
• meroplankton spend only a portion of their life cycle in the planktonic stage (e.g larvae of many larger organisms)
• plankton abundance and distribution are dependent on nutrient availability, water temperature and stratification and the abundance of other plakton
• 1mm = 1000 micrometers
• picoplankton = < 2 micrometers
• nanoplankton: 2 - 20 micrometers
• microplankton: 20 - 200 micrometers