Coral Reefs! Coral Reefs!
Coral in General • Phylum Cnidaria and the class Anthozoa • There are over 800 known Hermatipic species • Hermatipic- reef building • Coral reefs are the most biologically diverse ecosystems on earth, • Source of food • Protect coastlines (from storms and erosion) • Gives homes and spawning and nursery grounds for fish • Provide jobs to local economies from fishing, recreation, and tourism • New medicines
Soft coral!! • Also known as ahermatypic (non reef building) coral, they do not produce a calcium carbonate skeleton • Often called octocorals • Mostly colonial • Contains sclerites in cells on the outside of the colony found in coenenchyme, (jelly-like tissue) between polyps. • Sclerites made of protein and calcium carbonate. • Some are also encrusting
More coral, yippee • Hermatipic- Reef building coral • Contains a basal plate • Net benefit of the world's coral reef ecosystems estimated to be $29.8 billion per year • Have zooxanthellae • Deep water and some cold water corals lack zooxanthellae • Most corals feed at night • Similar to sea anemones. Polyps extend their tentacles to capture prey, first stinging them with toxic nematocyst cells, then drawing them toward their mouths. • Also collect fine particles in mucous film which are drawn by cilia into the polyp's mouth. Some species are entirely mucous suspension feeders • Prey ranges in size from small fish to zooplankton, depending on size of the coral
Deep Water Coral • Deep sea corals live on in deeper water from 50 m to over 3,000 m • A few species also live in shallower, cold water in the northern latitudes. • Found in all oceans • Like their shallow-dwelling relatives, deep-sea corals exhibit high biodiversity. • Don’t contain zooxanthellae (no light) • Don’t know the extent of communities because they live so deep • http://www.youtube.com/watch?v=PUbaVZRIS18
Zooxanthellae • an algae that gives off oxygen and other nutrients • polyp gives the algae carbon dioxide • That is why coral reefs grow near the surface • Algae enhance the coral’s ability to synthesize calcium carbonate • Coral Bleaching • When algae leave, due to warmer than usual water or a change in pH • http://www.youtube.com/watch?v=aEdoizgeNJk • http://www.youtube.com/watch?v=60jof35WuAo
Coral feeding • Feed similar to sea anemones. Polyps extend their tentacles to capture prey, stinging them with nematocyst cells, then drawing them toward their mouths. • Also collect fine particles in mucous film which are drawn by cilia into the polyp's mouth. Some species are entirely mucous suspension feeders • Prey ranges in size from small fish to zooplankton, depending on size of the coral
Reproduction, whoo babies Can be either asexual or sexual • Budding- asexual • new polyps bud off from parent. This occurs when the parent polyp reaches a certain size and divides. Continues throughout the animal's life and produces polyps identical to the parent polyp. • Fragmentation- asexual • Allows a portion of an entire colony to establish a new colony. The separated individuals start new coral colonies that are genetically identical to the parent colony
More babies • Broadcast Spawning • 3/4ths of all stony coral species are broadcast spawners • Produce male and/or female gametes that are released into the water in large numbers • Allows them to spread their “children” over a broad area. • Have lots of kids at one time to compensate for how many die a terrible depressing death, while their parents watch, and cant do anything about it. • occurs as a synchronized event, very important because male and female corals cannot move. • Usually occurs in response to environmental cues. • Long-term cues may be related to temperature, day length, or rate of temperature change. • The short-term control is usually based on lunar cues • http://www.youtube.com/watch?v=1aX61LzmeYA • http://www.youtube.com/watch?v=wsaZ8-I7akg
Yet more chilrin • Remaining 1/3 of coral species are brooders • Only male gametes released into water. • The gametes are negatively buoyant and transported by waves and current before sinking • They are taken in by female coral polyps containing egg cells fertilization occurs inside the female coral and produces a small planula. • The planula is released through mouth of female when it is old enough to settle very soon after its release.
Two ways for coral to get space • Overtopping • used mostly by fast growing species • The faster growing coral just grows over the other coral • The covered coral gets less light and food. • Aggression • involves extruded digestive filaments and sweeper tentacles. Typically results in the death of some of the other’s polyps. • http://animal.discovery.com/video-topics/wild-animals/coral-nighttime-battle.htm
Coral polyps themselves • Cells are specialized to perform various functions • Very limited organ development • Have a simple stomach (gastrovascular cavity ) opens only on one end, and a ring of tentacles. • No central nervous system. • While appearing to be a single organism, many coral are actually a colony of many individual, identical, coral polyps. • Are only a few millimeters in diameter
More polyps • The polyps of hard corals sit in a calyx that is produced by the coral with calcium carbonate • The walls surrounding the calyx are called the theca and the bottom is the basal plate. • Basal plate is a calciferous ring with six supporting ridges. The ridges grow vertically and project into the base of the polyp. • Tabulae are horizontal partitions that allow for upward growth by isolating the surface from the skeleton.