Over many years of development,¥σπ® stony polyps can form huge reef structures.β¶↑ Coral reefs are formed when c♠€oral polyps secrete calci§₹um carbonate. Most stony corals have very small ÷€polyps, averaging only 1 to 3 ←♣≠₽mm in diameter, but en÷÷¥tire colonies can grow very lar≤™ge, weighing several tons. As they grow, the¶β se reefs provide structural φ"Ω∏habitats for hundreds↔α• of different vertebrate and inve≠®rtebrate species.
Stony corals grow as individual polyps lift up$'®✘ from the bottom of the cavity they inhab♣•∞it and form a new fo→ ≠undation on top.
The skeleton of stonyΩ∞® corals is secreted by the lower half of the pφδolyp. This process produces ☆♥a polyp base that re€÷sembles a cup. The wall sur§¶>rounding the cup is cal✘₩≈led the "container", while the bo©♦ttom surface is called the "substrat♥"e". Periodically, a poε<♠πlyp will lift from its base ×±and secrete a new sub≤&strate on top of the old b♠'ase, creating a small ₹δ© chamber in the skeleton. While the ≈β↔colony is alive, calcium carbona&♥ε₩te is stored, increasing zoning and elev÷¥ating corals.
When the polyps are physically stressed, they s<Ω ♦hrink into their cavities so that nothing i☆"↓§s exposed on their ske≈Ω∑≤leton. This protects i≥÷t from predators. Normal¥ ly, polyps stick out from the cavityσ÷. Most polyps reach farther when feeding.γ♦≠
Reef-building corals c¥$ome in a variety of shapes. For example, brancσγ εhed corals have primary and secondar≥§y clades.
Branch corals are characterized¥± by many branches, often with secon≤♦dary branches. This huge branchin'÷€g coral colony belong© ₽s to the family Kochi and was observed on F remen Shoals in France, one of the maβ★ λny reefs that make up the ch♥ain of Northwest Hawaiian Isl αands.
Finger corals look li>φ€ke fingers without any secondary γbranches.
These pillar-like corals are a type of coπ©ral called finger corals, which grow on pilla☆≈•÷rs. Finger corals are distinguished fr←λβ↕om branching corals becauπ§$se they do not have secondary branches.
Table corals form table-like structures ¶φδthat are often fused together.
Corals that form broad horizontal planes are o£♥×&ften referred to as "table cor≠¶®als". This growth pattern incr≤" eases the coral'♣s exposed surface area ↓♠to the water column. Pol☆÷£yps are given greater light to access their zoox♦≥anthellae, and their tentacles can mor®↓e easily feed on zooplankton.
Acropora has large, flat bra >nches
Acropora has a unique growthλδ÷± pattern with unusually thick and sturdy ant≠ ≤-like branches. Staghorn corals usually g₩row rapidly, with branches increasing® by 10-10 cm per year.✔✘↓ This coral usually liv>£♦es in areas of high ↔wave activity.
Phyllophosphaeroides has extensive disc-like&♠ sections in an ascendi≈ng pattern that resembles a spi₹→♥ ral
Corals with leaf-like or spiral-like growth pattσ£erns form beautiful structures compared to★©¥' the open petals of the petals. The folds a≈λnd turns of the coral greatly£✘← increase its surface area, whil•®e the spaces in between can provide shelter for →≠fish and invertebrates.
Lumpy corals are spherical, or rock-like, '¶'may be small, like an egg, or σ☆≥as big as a house
Giant corals are typicΩ€→&ally spherical or relatively slow-growing corals.∏Ω Because of their veryλ★ stable shape, they are rarely damaged byβ₽ strong wave action.
Mushroom coral is like the attachment α¥ of mushrooms
Mushroom corals are usually flat α±£αor dome-shaped, round or oval€λ€, and shaped like th✔•✔e caps of mushrooms. Most mushroom∑♦×-shaped corals are solitary creatures, n ≠ot attached to any underlying substrate. ≤→They are found in Indo-Paciλ•↔§fic waters.
---From "NOAA"