Info about Organisms

Background Information on Algae, Brine Shrimp and Bacteria (usually given to students on Day 1)

ALGAE

Algae are photosynthetic organisms that occur in most habitats, ranging from marine and freshwater to desert sands and from hot boiling springs to snow and ice. Algae vary from small, single-celled forms to complex multicellular forms, such as the giant kelps of the eastern Pacific that grow to more than 60 meters in length and form dense marine forests. Algae generally do not have vascular tissue, and they do not show the high level of organ differentiation of the familiar, more complex plants.

The algae in the sphere are a type of green algae which are classified in the plant kingdom. They are photoautotrophic, which means that they can make their own food materials through photosynthesis by using sunlight, water, carbon dioxide. They also require other nutrients for growth and survival such as nitrogen (NOx) and phosphorus (POx). In common with all plants, green algae contain chlorophyll-a, as well as various other photosynthetic pigments. Most green algae can be represented by the chemical formula C₁₀₆H₂₆₃O₁₁₀N₁₆P.

BRINE SHRIMP

The brine shrimp, Artemia, belongs to the phylum Arthropoda (joint-legged invertebrates), class Crustacea (shrimp, crab, lobster). There are several species of Artemia worldwide. Brine shrimp live in salt water. They start their lives as tiny eggs, or cysts. As adults brine shrimp get all of their nutrients by feeding on algae. Brine shrimp excrete their solid waste in the form of ammonia (NH₃).

Adult Artemia average about 0.32" (8mm) long, but can reach lengths up to 0.78" (20mm). Adults can tolerate brief exposures to temperatures as extreme as 0^o to 104^o F (-18^o to 40^o C).

BACTERIA

Bacteria consist of only a single cell, but are an amazingly complex and fascinating group of creatures. Bacteria are neither plants nor animals, but belong to the Domain Prokaryotes. Two different types of bacteria found in the ecosphere, heterotrophic and nitrifying bacteria, are described below. Both types of bacteria are largely non-motile and must colonize a surface (gravel, sand, etc.) for optimum growth. They secrete a sticky slime matrix which they use to attach themselves.

Heterotrophic Bacteria

Heterotrophic bacteria require an organic carbon source for growth; i.e. derive energy and carbon from organic compounds. They generally obtain their nutrients and energy by decomposing organic debris (dead algae, for example). Most heterotrophic bacteria utilize oxygen in the decomposition process. Heterotrophic bacteria can double (reproduce) their numbers in as short a time as 20 minutes.

Nitrifying bacteria

Another category of bacteria, nitrifying bacteria, cannot breakdown organic materials, but rather must convert ammonia (NH₃) to oxides of nitrogen (NOx) for their energy needs. These bacteria also require carbon dioxide (CO₂) to fulfill their carbon requirements. They are obligate aerobes (need oxygen) and cannot multiply or convert ammonia in the absence of oxygen.

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