Trivia Tuesday: 10 Facts About Corals

coral reef
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We love animals. In fact, we love them so much that we geek out over learning little-known animal facts, and we suspect we're not the only ones. Each Tuesday, we'll share a few fun animal facts with you from experts at zoos, parks and aquariums all over the country (and maybe even beyond). Since it's summer, we're focusing on animals of an aquatic nature.

10 Things You Don't Know About Corals

Today's expert: Mark Schick, Special Exhibit Collection Manager at Shedd Aquarium.

Schick has been working with Shedd for more than 15 years, and has been studying corals for close to 20 years.

  • Corals have been around for hundreds of millions of years, which is particularly impressive when you consider the fact that water levels have changed hundreds of feet in that time.
  • Although coral makes up considerably less than one percent of the ocean floor, it's estimated that 70 percent of oceanic fish spend at least part of their life in and around coral.
  • Most coral (99 percent) spend their entire life in one spot on the ocean floor.
  • Coral is colorful because of the algae growing inside it.
  • Coral and algae have a symbiotic relationship. Coral provides shelter for the algae, and algae creates more food than it needs, which it then throws out to the coral.
  • The sea floor where coral lives is a veritable war zone. Although they don't move, coral fight each other in a variety of ways, such as growing quickly so as to overshadow another nearby coral, thus starving it of sunlight, or growing in such a way so as to block or change the flow of water going to the other coral.
  • Water flow is vitally important to coral. It both brings nutrients to the coral and allows the coral to expel waste.
  • Coral has just one opening, so everything (food, waste, etc.) goes in and out of a single hole.
  • Only the thin veneer on top of a coral is a living animal. It lives on top of calcium rock that it's created; coral basically builds a house on top of a house on top of a house, which is how it can grow to be so large.
  • Coral asexually divides, and some species, such as the Elkhorn in the Caribbean, cannot self-fertilize, so it releases polyps of egg and sperm, which float to the top and mix with polyps from other coral. Unfortunately, this coral is endangered and is now so spread apart that it doesn't have much of a chance to mix and create larvae. Organizations like SECORE (with which Schick is involved) are working to bring together coral from different parts of the Caribbean to ensure the species survives.

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