How to Make an Ecosystem in a Glass Sphere

Sealed ecosystems will survive at least one month and up to several years depending upon light and proper nutrient balance.
Sealed ecosystems will survive at least one month and up to several years depending upon light and proper nutrient balance. (Image: glass window object image by Aaron Kohr from

Imagine capturing an Earth-like habitat in a glass bottle. Science fiction writers and modern day scientists have labored and accomplished this very task. Elementary school students create terraform ecospheres in glass bottles, and scientists wonder what it would be like to create glass-enclosed human habitats under the sea or out in space. While man-made ecosystems for humans are centuries away from successful engineering, the creation of a miniature enclosed ecosystem is well within our grasp. The trick to building a self-sustainable ecosystem is finding the proper balance of elements, microbes and living creatures and providing them with the proper amount of warmth and light.

Things You'll Need

  • 1/2-gallon glass sphere with a flat glass cover
  • 1/2 cup natural sand or lake soil
  • 6 cups lake water
  • 1/8 cup freshwater algae strands
  • 1 twig
  • 1 freshwater fish
  • 5 small freshwater worms
  • 1 freshwater snail
  • Heavy-duty glass adhesive
  • 1 sphere stand

Sterilize the glass sphere by warming the glass in boiling water. This will remove any leftover oils, minerals and residue from the manufacturer.

Place the sand or lake soil in the base of the sphere. Natural sediment contains bacteria and microbes that will provide necessary nutrients to the animal and sea life in the sphere.

Gently pour the lake water into the sphere. The sphere should be three-quarters full, because your ecosystem requires air. Allow the sediment to settle before adding the plant or sea life.

Wrap the algae strands loosely around the twig. Place the twig upside down in the jar. The top of the twig should point into the sand.

Place the worms, small fish and snail gently into the sphere. Give these creatures several hours to become accustomed to their new home prior to sealing the sphere.

Apply adhesive to the edges of the glass lid and press it securely over the base of the sphere. Place a heavy object (like a book) over the lid to apply pressure and promote a good seal. Allow the sphere to rest for the length of time the adhesive requires to dry.

Swirl the sphere gently in circular motions to loosen the sediment from the top of the sphere. Turn the sphere slowly upside down and rest it on a stand. Be sure that all sediment is cleared from the top of the sphere, or it will create a film and prevent light from entering the glass.

Place the ecosystem in indirect light. The algae grows more when it receives more light, but if it grows too much, it will suffocate the fish, worms and snail.

Tips & Warnings

  • Collect sand from the same environment as the water (lake, river or sea).
  • Your ecosystem will survive on the nutrients you have added (the animal life, plant life and natural elements) and sunlight. Once the sphere is sealed, the only element you control is sunlight.
  • Stay attentive to algae growth, as this will determine how much light or darkness your sphere needs to remain sustainable. Too much algae means the sphere is getting too much natural light; too little algae means there is a lack of sufficient light.
  • An enclosed ecosystem can be created with any shape or style of glass container. Try several different sized and shaped containers to create a display of varied ecosystems.
  • You can use any small fish or other sea life, so long as there are enough nutrients for all creatures to survive. Larger ecosystems allow you to use larger animals.
  • Keep the sphere away from direct sunlight. Direct sunlight could cause the fish and other sea life to perish from overheating.

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