Although corals can catch small fish and plankton, using stinging cells on their tentacles, most corals obtain the majority of their energy and nutrients from photosynthetic unicellular algae called zooxanthellae that live within the coral's tissue.

Although corals first appeared in the Cambrian period, some, fossils are extremely rare until the Ordovician period, 100 million years later, when rugose and tabulate corals became widespread.

Although they are geologically younger than the tabulate and rugose corals, their aragonitic skeleton is less readily preserved, and their fossil record is less complete.

Although deep water corals can form reefs, very little is known about them.

Although corals are major contributors to the framework and bulk material comprising a coral reef, the organisms most responsible for reef growth against the constant assault from ocean waves are calcareous algae, especially, although not entirely, species of coralline algae.

Although corals feed nocturnally on plankton, sunlight

Although there is no direct proof, it is inferred that these Palaeozoic corals possessed stinging cells to capture prey.

Although the solution is thought to be effective when used with stony corals, systems containing xenia and soft corals are assumed to be particularly benefited by the use of Lugol's solution.

Although the biomachinery facilitating biomineralization is complex – involving signalling transmitters, inhibitors, and transcription factors – many elements of this ' toolkit ' are shared between phyla as diverse as corals, molluscs, and vertebrates.

“ Although deeper-water corals form reefs in the dark of ocean depths, Pulley Ridge is the deepest photosynthetic coral reef that we know of today ,” said Robert Halley, USGS marine geologist .” Other reefs lie about 46 meters below sea level.

Although no national norms exist for the social development of children, the teacher can find a great deal of information concerning types of social behavior normally displayed by children at various age levels.

Although Utopian communism is both new in 1516 and also modern, it is not modern communism or even modern socialism, as they exist or have ever existed in theory or in practice.

Although this technique is simple and satisfactory, one practical difficulty does exist: the direction of true north must be known for each launch point.

Although the theological forms of the past continue to exist in a way they do not in a more secularized situation, the striking thing is the rapidity with which they are being reduced to a marginal existence.

Although most stand alone in the landscape, some examples exist of brochs surrounded by clusters of smaller dwellings.

Although the German General Staff was also abolished by the treaty, it nevertheless continued to exist as the Truppenamt or " Troop Office ", supposedly only an administrative body.

Although there is no strong evidence for any single theory, many independent theories exist, some blaming storms, some capsizing, and some suggesting that wartime enemy activity was to blame for the loss.

Although earlier precursors to this presentation exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869, who intended the table to illustrate recurring trends in the properties of the elements.

Although technology does not exist currently to measure this, it can be estimated by determining oxygen consumption by the brain.

Although rare, deposits of native chromium exist.

Although the isosahedral structure is extremely common among viruses because of size differences slight variations exist between virions.

Although professional cheerleading leagues exist in multiple countries, there are no Olympic Teams.

Although once thought to be a simple solution of molecules, multiple levels of organization exist in the cytosol.

Although most economies today are market economies or mixed economies ( which are partially planned ), fully planned economies exist in the remaining few countries of Cuba, Libya, North Korea, Saudi Arabia, Belarus, and Myanmar.

Although the abuses and atrocities that characterized the Macias years have been eliminated, effective rule of law does not exist.

Although humans exist and operate within ecosystems, their cumulative effects are large enough to influence external factors like climate.

Although humans exist and operate within ecosystems, their cumulative effects are large enough to influence external factors like climate.

Although seldom used in modern times, Edlin may sometimes be used as an Edlin-script interpreter, in environments where no other editors exist.

Although evidence-based medicine is regarded as the gold standard of conventional clinical practice, limitations or criticisms of its use exist, such as:

Although exceptions exist, the first day of the bis sextum ( February 24 ) was usually regarded as the intercalated or " bissextile " day since the third century.

Although no " Hopkinson flags " exist from the time period, it is believed that his flag contained 13 red and white stripes and 13 white stars arranged symmetrically on a field of blue.

Although many shelters still exist, some even being used as museums, virtually all fallout shelters have been decommissioned since the fall of the Soviet Union in 1991.

Although the problem is not known to be in NC, parallel algorithms with time superior to the Euclidean algorithm exist ; the best known deterministic algorithm is by Chor and Goldreich, which ( in the CRCW-PRAM model ) can solve the problem in O ( n / log n ) time with n < sup > 1 + ε </ sup > processors.

Although semitisms exist throughout the Gospel of Luke, it was composed in Koine Greek.

Although many regulations that discriminated against non-Christians — including Jews and other minority groups — had been eliminated during the unification of Germany in 1871, antisemitism continued to exist and thrive in Germany and other parts of Europe.

Although in both emotions sympathetic symptoms are present, different autonomic-somatic patterns underlie aggression and anxiety, respectively, as indicated by the rate of the excretion of the catecholamines, the state of the muscle tone, and the Mecholyl test.

Although both concede they would like to hit 60, they stick primarily to the baseball player's standard quote: `` The important thing is to win the pennant ''.

Although Tylor undertook a field trip to Mexico, both he and Frazer derived most of the material for their comparative studies through extensive reading, not fieldwork, mainly the Classics ( literature and history of Greece and Rome ), the work of the early European folklorists, and reports from missionaries, travelers, and contemporaneous ethnologists.

Although blind students have benefited from talking calculators, the abacus is still very often taught to these students in early grades, both in public schools and state schools for the blind.

Although " android " is used almost universally to refer to both sexes, and those of no particular sex, " android " technically refers to the male form, while " gynoid " is the feminine form.

Although constrained by land mass and topology, the amount of arable land, both regionally and globally, fluctuates due to human and climatic factors such as irrigation, deforestation, desertification, terracing, landfill, and urban sprawl.

Although single genes have little effect on complex traits and interact heavily both between themselves and with the external factors, research is underway to unravel possible molecular mechanisms underlying anxiety and comorbid conditions.

Although Romanticism and Neoclassicism were philosophically opposed, they were the dominant European styles for generations, and many artists were affected to a greater or lesser degree by both.

Although " Takes A Little Time " was a moderate hit single, the album failed to sell like the previous two albums, which had both gone multi-platinum.

Although Housman's early work and his sphere of responsibilities as professor included both Latin and Greek, he began to focus his energy on Latin poetry.

Although both polysaccharide classes share the same galactose-based backbone, agaropectin is heavily modified with acidic side-groups, such as sulfate and pyruvate.

Although both actors had separate careers, their filmed dance sequences together, which included portrayals of the Castles, have reached iconic status.

Although the holiday may use features of the Gaelic Beltane, such as the bonfire, it is more alike the Germanic May Day festival, both in its significance ( focusing on fertility ) and its rituals ( such as maypole dancing ).

Although it's increasingly common for couples – particularly younger couples – to have " power neutral " relationships and / or play styles, activities and relationships within a BDSM context are often characterized by the participants ' taking on complementary, but unequal roles ; thus, the idea of informed consent of both the partners becomes essential.

Although Captain Du Petit Thouars had lost both legs and an arm he remained in command, insisting on having the tricolour nailed to the mast to prevent it from being struck and giving orders from his position propped up on deck in a bucket of wheat.

Although there were many IRA men — both Official and Provisional — present at the protest, it is claimed they were all unarmed, apparently because it was anticipated that the paratroopers would attempt to " draw them out ".

Although 19th-century ethnologists saw " diffusion " and " independent invention " as mutually exclusive and competing theories, most ethnographers quickly reached a consensus that both processes occur, and that both can plausibly account for cross-cultural similarities.

Although clearly both genetic and environmental input is needed for a child to develop normally, considerable debate remains about how genetic information might guide cognitive development.

Although there are conflicting dates as to when they met ( some sources state that they met in January 1989 at the Satyricon nightclub ), Love stated that the two first encountered one another in January 1988 at a Dharma Bums show where she was doing a spoken word performance, and Erlandson stated that both he and Love were formally introduced to Cobain in a parking lot after a Butthole Surfers concert at the Hollywood Paladium in 1991.

Although the perception by the public may be that the " central bank " controls some or all interest rates and currency rates, economic theory ( and substantial empirical evidence ) shows that it is impossible to do both at once in an open economy.

Although the ČSLA, as formed in 1945, included both Soviet-and British-equipped / trained expatriate troops, the " Western " soldiers had been purged from the ČSLA after 1948 when the communists took power.

Although his term lasted only six months instead of twelve ( except for the Dictatorships of Sulla and Caesar ), all other magistrates reported to the dictator ( except for the tribunes of the plebs-although they could not veto any of the dictator's acts ), granting the dictator absolute authority in both civil and military matters throughout the Republic.

Although the public generally associates carcinogenicity with synthetic chemicals, it is equally likely to arise in both natural and synthetic substances.