Conveyor Belts of Mucus - Water Flow On & In Our Corals

Mucus. Hydrodynamics. Coral Biology. They seem like such different topics, but there's really a lot going on in coral - on and under the polyps on surfaces of the colorful corals in our reef tanks.

Acropora, Montipora, Acanthastrea... they all can create complex currents in the water near them using tiny hairs. Many, including all our SPS, create interior networks and channels (called a gastrovascular system) where water and material can be moved all over the colony. On their surface, the water networks can move fluid onto exposed coral during low tides, or coral that is exposed in our tanks during water changes. That helps prevent the coral from drying out - something that would be very bad for the coral.

We often think of corals as being made up of thousands of individual polyps - each able to survive on its own. That's true, but they gain a lot from being in a colony. They can work together to capture prey by secreting mucus, and they can share food and nutrients using channels connecting them under the surface. Lots of Symbiodinium algae also live in the walls of these tunnels, contributing energy back to the connected polyps.

Our reef tank corals use mucus for a bunch of things. From cleaning their surface to capturing food items, all that slime is an important part of a coral's life.

All the incredible videos I showed in this video are from the paper just below. I encourage you to check it out for even more detail on the topics I covered if you're interested in marine biology and hydrodynamics.

Bouderlique et al., Surface flow for colonial integration in reef-building corals, Current Biology (2022), https://doi.org/ 10.1016/j.cub.2022.04.054

The slime dripping off the coral is from:
Islam, M. N., Casareto, B. E., & Suzuki, Y. (2016). Eutrophication Accelerates Carbonate Dissolution under High pCO2 Condition in Coral Reef Ecosystem. Journal of Scientific Research, 8(3), 427–438. https://doi.org/10.3329/jsr.v8i3.27937

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