A-z - Animals

What eats algae?

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Did you know experts say algae could be the food of the future? According to the BBC, microalgae are rich in amino acids, proteins, fatty acids and vitamins. Even the Journal of Applied Phycology considers algae as a nutritional and functional food source for animals and humans.

Are you still wondering why algae are essential and what is responsible for forming the energy base of the food web for nearly all water-based organisms? We'll cover all of this further in this article.

What are algae?

lawn mower bunny
Algal catfish in a reef aquarium.


Algae are a group of aquatic, autotrophic, nucleated organisms of the kingdom Protists, without true roots, leaves, or stems. They also lack unique cell and tissue types found in other plants, such as phloem, stomata and xylem, but produce food that in turn provides the energy base for other organisms.

These photosynthetic organisms produce food internally and reproduce through sexual or asexual (vegetative) reproduction methods. Algae thrive in freshwater lakes or saltwater oceans and tolerate a wide range of temperatures. Some algae live on land and grow in unexpected places like tree trunks, animal fur, snowdrifts, hot springs and soil.

The importance of algae

To put it bluntly, algae are huge contributors to our environment and to other living things, as they produce oxygen for all living things through photosynthesis. These aquatic nucleated organisms produce up to 50 percent of the oxygen in Earth's atmosphere, which humans and other organisms use to breathe. Surprisingly, they don't compete with plants, but they serve as fertilizers to help grow crops efficiently. In addition to their many properties, they boost the immune system of fish, improve the fitness of marine invertebrates, provide an attractive natural appearance to the aquarium, and help clean the aquarium ecosystem as a form of filtration. With such high regard for these autotrophs, we'd be wise to dig a little deeper to find out where in the food chain they occur and what algae they typically eat.

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What eats algae?

Zooplankton, tadpoles, and crustaceans feed on the algae.

©iStock.com/Goran Safarek

Many aquatic consumers, such as zooplankton, tadpoles , algavores (algivore), small fish, crustaceans, and aquatic insects, rely on algae as their main food source . Snails, crabs, and sea urchins also eat algae, but they have been known to eat red sticky algae, green membrane algae, hair algae, phaemenium algae, and many other types of algae in saltwater.

Generally, these various species of aquatic consumers feed on algae, and interestingly, along the food chain, they become prey to larger marine organisms such as fish – which humans feed on. In fact, algae are the basis for the different energy productions of plants and animals. Let's take a look at what eats algae one by one.


In freshwater, some fish such as plecostomus, kuhli loach, otocinclus, bristlenose pleco, Siamese algae-eater, Chinese algae-eater, flying fox, and mountain stream loach feed on algae.

Plecostomus are a group of omnivores that include sucker catfish of various sizes. Diet choices for plecos vary, and they will eat anything on the menu, from algae, fish food, thawed frozen food, wood fiber, shrimp, to insects.

Octocinclus eats algae and biofilms, which accumulate on plants and rocks.

The Chinese algae-eating fish is a unique small sucker fish, interestingly, the shape of its sucker mouth allows it to forage algae efficiently on rocks and plants.

On the other hand, mountain stream loaches eat algae. However, they cannot survive long-term on these diets alone unless their diets contain a variety of other high-quality nutrients.


Biggest Shrimp – Pink Shrimp
As opportunistic omnivores, shrimp eat algae.

© Spayder pauk_79/Shutterstock.com

Shrimp are also excellent algae eaters in freshwater — these sea creatures are opportunistic omnivores, eating everything from algae to plankton. Fascinatingly, they are not selective about what they eat, so by default they will eat all types of algae, especially if they collect on hard surfaces in tanks or ponds. Some popular shrimp species known to eat algae include ghost shrimp, cherry shrimp, amano shrimp, bamboo shrimp, grass shrimp, snowball shrimp, bee shrimp, and Sulawesi cardinal shrimp.

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Many snails in freshwater, including shallow sea snails, apple snails, Ramshorn snails, rabbit snails, pond snails, Malaysian trumpet snails, and sun snails, eat algae. Snails play an important role in maintaining freshwater aquariums by removing algae, dead plant material, dead fish, and other debris. The incredible importance of these snails is that they inhabit freshwater aquariums, helping to recycle waste and reduce tank maintenance requirements.


Crabs are omnivores, and interestingly, they like to eat protein and algae. Two common species of algae-eating crab are the sally lightfoot crab and the common mithrax crab. Several crabs inhabit the bottom of the sea, under rocks and coral reefs. When crabs inhabit these aquatic habitats, they prey on food such as algae, organic matter, carcasses and waste. With the help of their claws, these adorable sea creatures grab food and put it in their mouths.

sea urchin

What do sea urchins eat - sea urchin mouth
Sea urchins eat seaweed with the help of their teeth.

© narupong sooknatee/Shutterstock.com

Sea urchins are good algae eaters, congregating mainly in cooler inshore waters. Interestingly, they will enter shallow water in search of food. Sea urchins possess a structure called an Aristotelian lantern, consisting of five rigid plates that come together like a beak to enable them to feed. They scrape algae off rocks with their beaks. Their sharp teeth can also crush plankton, kelp, periwinkle, and sometimes even barnacles and mussels. Fascinatingly, they can regenerate teeth to replace worn ones.


Tadpoles are primarily herbivores, eating soft vegetation such as duckweed, moss, and algae. In fact, they are too small to eat the same food as frogs. Their diet varies by species, but for the first few days after birth they will insist on a diet of algae.

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other algae-eating animals

  • Some turtles (wood turtles, sea turtles, Midland painted turtles, red-eared turtles eat algae)
  • Antarctic krill
  • salamander
  • centipede

List of animals that eat algae

Here is a list of animals that eat algae:

  • fish
  • tadpole
  • snails
  • Plankton
  • bluegill
  • shrimp
  • centipede
  • Crab
  • sea turtle

Are Chlorella Herbivores?

Algae are generally classified as plants rather than animals, and they are sometimes considered protists. Chlorella are neither herbivores, carnivores, nor omnivores, and fascinatingly, they make food through photosynthesis.

How do algae defend themselves?

It is impossible for any creature to be eaten without wanting to defend itself. Some algae, especially those rich in calcium carbonate, are complex, mostly rocky, and unattractive, so they tend to use their traits to ward off predatory herbivores. These aquatic autotrophs also produce defensive chemicals to protect themselves from predators. Chlorella and the like contain high concentrations of toxic protective chemicals to keep herbivores from eating them.


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