Corals Flashcards
What are corals?
animals related to sea anemones; colonial organisms
Basic structure of a coral
the polyp
Nematocysts
stinging cells on the end of coral tentacles; target small organisms that get too close, using them as food source
What resides within the polyp?
digestive and reproductive tissues
What is a coral skeleton composed of?
calcium carbonate
Zooxanthellae
single-celled algae
Explain the symbiotic relationship between coral and zooxanthellae
coral is the host, zooxanthellae photosynthesize to produce food, providing some nutrition for the coral; in exchange, the coral provides nutrients
What are most tropical reefs composed of?
true stony coral (each polyp sits in calcium carbonate cup)
What are the most important reef builders?
stony corals
Anthozoans
class of Cnidarians; carnivorous; asexual or sexual reproduction
2 categories of anthozoans
hexacorals and octocorals
Hexacorals
have smooth tentacles, often in groups of six (ex: true stony corals, black corals, sea anemones)
Octocorals
have eight tentacles, each having tiny branches along the sides (ex: soft corals, blue corals, seafans, organpipe corals)
What phylum do corals fall under?
Cnidaria
Asexual vs. Sexual Reproduction
asexual important for increasing colony size; sexual important for increasing genetic diversity and creating new colonies
Asexual Reproduction
results in cloned polyps or colonies
Budding
a coral polyp reaches a certain size, dividing to produce a genetically identical polyp
Fragmentation
a piece of a colony breaks off to start a new one
Sexual Reproduction
sperm fertilizes eggs, often coming from other colonies to do so; eggs grow into free-swimming larva
2 forms of Sexual Reproduction
external and internal
External Reproduction
larvae settle on suitable substrate, grow into polyps; colonies release a ton of eggs and sperm into the water
Mass Spawning
large spawning event that usually occurs at night; spawning usually only happens once a year
Internal Reproduction
corals brood their eggs in the body of a polyp and release sperm into the water; as sperm sinks, polyps containing eggs take them in and fertilize them
What is the typical size of an individual coral polyp?
less than half an inch
What is the structure of a reef system, from smallest to largest?
coral joins other corals to form a colony, colonies form reefs
Fringe Reefs
reefs that fringe along the coastline of a nearby landmass
How fast can corals grow?
6 inches per year
What is the typical speed of coral growth?
less than an inch per year
Where are reef-building corals found?
in shallow tropical and subtropical waters
Where do deep-sea corals thrive?
in dark, cold water
Characteristics of deep-sea corals
do not have zooxanthellae, do not need sunlight or warm water to survive, grow very slowly, can be found on seamounts (underwater peaks)
