How Do Corals Eat? Coral Feeding Explained

Q: What are the main ways corals get nutrition?

Corals generally rely on a combination of three pathways, though the relative importance varies a lot by species: photosynthesis, via the zooxanthellae living in their tissue, which for many shallow-water reef-building corals is a major or even primary energy source; capturing prey — typically small zooplankton and other particles — using tentacles armed with stinging cells called nematocysts; and absorbing dissolved organic matter directly from the surrounding water, without capturing a discrete particle at all. Most corals use more than one of these simultaneously, which is part of why 'do I need to feed my coral' (covered for one species in our hammer coral feeding guide) often has a nuanced answer rather than a flat yes or no.

Q: How does a coral actually capture and eat a piece of food?

When a polyp's tentacles are extended, they're armed with nematocysts — specialized stinging cells (the same general category of structure found across Cnidaria, including the anemones covered in our anemone feeding guide) that can immobilize small prey on contact. Captured food is then drawn toward the polyp's central mouth, which leads to a body cavity where digestion occurs. Notably, a coral polyp has only one opening — the same opening serves as both mouth and anus, with food going in and waste products eventually coming back out through that same opening. This is a simpler digestive arrangement than animals with separate mouth and anus, consistent with the simple nerve net and overall body plan of corals and their relatives.

Q: If zooxanthellae provide so much energy, why do corals bother capturing food at all?

Because photosynthesis alone often doesn't cover everything a coral needs, even when it covers a large share of energy requirements. Zooxanthellae are particularly good at supplying energy (in the form of photosynthetic products), but corals also need other nutrients — including nitrogen and phosphorus-containing compounds — that captured prey and absorbed organic matter can provide more directly. This is part of why feeding is often described as beneficial for growth and coloration even for corals that could technically survive on photosynthesis alone, a point covered in practical terms in our hammer coral feeding guide and our target-feeding guide. The two pathways are complementary rather than redundant — photosynthesis provides a steady energy baseline, while feeding can supply additional nutrients and supplemental energy.

By Hektor Jorgo Published August 6, 2024 Updated June 14, 2026 4 min read

A coral polyp with tentacles extended, capturing food particles from the water

Quick Facts

Three Feeding Pathways: Photosynthesis (via zooxanthellae), capturing prey with tentacles, and absorbing dissolved organic matter from the water
Primary Pathway for Most Reef Corals: Photosynthesis via zooxanthellae is often the largest single energy source for many shallow-water reef-building corals
How Prey Is Captured: Tentacles armed with stinging cells (nematocysts) capture and immobilize small prey like zooplankton
The Mouth Does Double Duty: A polyp has a single opening that functions as both mouth and anus — food in, waste out, through the same opening
Dissolved Organic Matter: Some corals can absorb dissolved nutrients directly from surrounding water, without capturing a discrete particle
Relative Importance Varies by Species: Some corals rely much more heavily on feeding/capture than others, which is part of why feeding recommendations differ between species
Tentacle Extension: Many corals extend tentacles more (or feed more actively) during low-light periods, though this varies by species
Why Feeding Is Often 'Supplemental': Because photosynthesis already covers a substantial portion of energy needs for many corals, direct feeding often supplements rather than replaces that baseline

"Does my coral need to be fed?" turns out to be a question with three possible answers happening at once — most corals are getting energy from sunlight, from captured food, and from the water itself, all at the same time, just in different proportions.

Short Answer

Corals generally combine three feeding pathways: photosynthesis via zooxanthellae, capturing prey (mainly zooplankton) with stinging tentacles, and absorbing dissolved organic matter directly from the water. As covered in our overview of what coral is, the zooxanthellae partnership is often the largest single energy source for many shallow-water reef-building corals — but captured prey and dissolved nutrients fill in gaps that photosynthesis doesn't fully cover, particularly for nutrients beyond raw energy. The relative importance of each pathway varies by species, which is part of why feeding recommendations differ between corals.

Pathway One: Photosynthesis via Zooxanthellae

As covered in our overview of what coral is, many corals host zooxanthellae — symbiotic algae living in their tissue that photosynthesize and share a substantial portion of the resulting energy with the coral. For many shallow-water reef-building corals, this is the largest single energy source, and it's the reason lighting is such a central topic in coral care (see our LPS lighting notes).

Pathway Two: Capturing Prey With Tentacles

When a polyp's tentacles are extended, they're armed with nematocysts — stinging cells that can immobilize small prey, mainly zooplankton and similar particles, on contact. This is the same general kind of structure found across Cnidaria, including the anemones covered in our anemone feeding guide. Captured food is drawn toward the central mouth, which is the polyp's only opening — it functions as both mouth and anus, with food going in and waste eventually coming back out the same way. This simple arrangement is consistent with the simple nerve net and overall body plan shared across corals and their relatives.

Pathway Three: Absorbing Dissolved Organic Matter

Less visually obvious than tentacle-feeding, some corals can also absorb dissolved organic matter directly from the surrounding water, without capturing a discrete particle at all. This pathway doesn't produce anything to observe directly, but it's part of the broader picture of how corals interact nutritionally with the water column — relevant to why water quality and dissolved nutrient levels matter for coral health beyond the more visible factors of lighting and direct feeding.

Why These Pathways Are Complementary, Not Redundant

Photosynthesis is particularly good at supplying energy, but corals also need other nutrients — including nitrogen- and phosphorus-containing compounds — that captured prey and absorbed organics provide more directly. This is why direct feeding is often described as beneficial for growth and coloration even for corals that could survive on photosynthesis alone, a point covered in practical terms in our hammer coral feeding guide and our companion target-feeding guide. Rather than one pathway being "the" feeding method and the others being backups, most corals are running all of these simultaneously, in proportions that depend on the species and conditions.

What This Means for Feeding Decisions

Because the relative importance of these three pathways varies by species, "does my coral need feeding" doesn't have a single universal answer:

Corals that rely heavily on zooxanthellae and have relatively small polyps may get by largely on light alone
Corals with larger polyps and more developed tentacle-capture abilities — like many hammer and torch corals — often show clearer benefits from direct feeding
All corals are affected to some degree by water quality and dissolved nutrients, regardless of how much they're directly fed

Our companion guide on target feeding corals covers the practical side of pathway two — how to actually offer food in a way a coral can capture and use.

Quick Reference

Corals generally combine three feeding pathways: photosynthesis, prey capture, and dissolved organic matter absorption
Zooxanthellae-driven photosynthesis is often the largest single energy source for many reef corals
Tentacles use stinging cells (nematocysts) to capture zooplankton and similar prey
A coral polyp has one opening that serves as both mouth and anus
Some corals absorb dissolved organic matter directly from the water
These pathways are complementary — feeding supplements photosynthesis rather than replacing it
How much a coral benefits from direct feeding varies by species and polyp size

Frequently Asked Questions

What are the main ways corals get nutrition?

Corals generally rely on a combination of three pathways, though the relative importance varies a lot by species: photosynthesis, via the zooxanthellae living in their tissue, which for many shallow-water reef-building corals is a major or even primary energy source; capturing prey — typically small zooplankton and other particles — using tentacles armed with stinging cells called nematocysts; and absorbing dissolved organic matter directly from the surrounding water, without capturing a discrete particle at all. Most corals use more than one of these simultaneously, which is part of why 'do I need to feed my coral' (covered for one species in our hammer coral feeding guide) often has a nuanced answer rather than a flat yes or no.

How does a coral actually capture and eat a piece of food?

When a polyp's tentacles are extended, they're armed with nematocysts — specialized stinging cells (the same general category of structure found across Cnidaria, including the anemones covered in our anemone feeding guide) that can immobilize small prey on contact. Captured food is then drawn toward the polyp's central mouth, which leads to a body cavity where digestion occurs. Notably, a coral polyp has only one opening — the same opening serves as both mouth and anus, with food going in and waste products eventually coming back out through that same opening. This is a simpler digestive arrangement than animals with separate mouth and anus, consistent with the simple nerve net and overall body plan of corals and their relatives.

If zooxanthellae provide so much energy, why do corals bother capturing food at all?

Because photosynthesis alone often doesn't cover everything a coral needs, even when it covers a large share of energy requirements. Zooxanthellae are particularly good at supplying energy (in the form of photosynthetic products), but corals also need other nutrients — including nitrogen and phosphorus-containing compounds — that captured prey and absorbed organic matter can provide more directly. This is part of why feeding is often described as beneficial for growth and coloration even for corals that could technically survive on photosynthesis alone, a point covered in practical terms in our hammer coral feeding guide and our target-feeding guide. The two pathways are complementary rather than redundant — photosynthesis provides a steady energy baseline, while feeding can supply additional nutrients and supplemental energy.

Can corals absorb food without 'eating' it in the normal sense?

Yes — some corals can take up dissolved organic matter directly from the surrounding water, without capturing a discrete prey item or particle at all. This is a less visually obvious feeding mode than tentacles capturing zooplankton, but it's part of the broader picture of how corals interact with the water column nutritionally. The practical relevance for aquarium keepers is mostly indirect: it's part of why water quality and dissolved nutrient levels matter for corals beyond just 'will my coral starve' — corals are interacting with dissolved compounds in the water in ways that go beyond what's visible, on top of the more obvious factors like lighting (for zooxanthellae) and direct feeding (for captured prey), both covered in our LPS beginner guide.

Sources & Further Reading

About the Author: Hektor Jorgo

Co-Founder & Marine Biologist

Hektor is a co-founder of Sea Life Planet and has kept reef and freshwater aquariums for over 15 years. He holds a background in marine biology and focuses on species care accuracy, water chemistry, and tank husbandry.