Marine and Freshwater Aquarium
Glossary of Terms

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

• adipose fin - The small fin located between the dorsal fin and the caudal fin. It seems to serve no purpose.
• anal fin - Single fin mounted vertically below the fish.
• anthostele - The lower part of the polyp, often stiffened, into which the distal portion of the polyp, the anthocodia (which includes the mouth and the eight tenacles) is withdrawn. The calyx.
• barbels - Barbels are the whisker-like appendages found on both sides of the mouth of all catfish.
• benthic - Benthos and benthic refers to living on or under the substrate at the bottom of the ocean. Sessile means the organism is attached to the substrate. Pelagic refers to living in the water of the ocean above the bottom. Pelagic organisms ususally have some ability to move around.
• brackish - water that is neither fresh nor saltwater, but is somewhere in between. In nature this occurs at the mouths of rivers and swamps near the sea. Some fish live in salt water but are spawned in brackish or fresh water and vice versa. There are several brackish species available in the aquarium hobby, see Freshwater Fish for descriptions.
• calcyes - plural for calyx. See anthostele.
• carnivore - Animals who hunt and eat other animals; meat eater. Sharks are a good example.
• carapace - A bony or hard shell that covers part or all of an animal. Turtles, crabs, and boxfish are good examples.
  
• caudal - The single fin mounted vertically at the rear of the fish. The tail fin.
  
• caudal penduncle - The part of the body which attaches the caudal (tailfin) to the body. The surgeonfish's spines are located on the caudal penduncle
  coelenterate - an aquatic animal of the Phylum Coelenterata which is characterized by a central mouth usually surrounded by tentacles bearing stinging cells, and no anus; includes sea anemones, corals, and jellyfishes.
  coenenchyma - the tissue of a zoanthid that surrounds the polyps. Consists of mesoglea and may have sand imbedded in it.
  
• comensal - A relationship where two or more different kinds of animals live together and one benefits while the other does not.
  
• conspecific - Refers to animals of the same species.
  
• detritus - Greyish piles of "mulm" that a accumulate in the aquarium.
  
• dorsal fin - The fin directly on the top of the body (it's the fin that sticks out of the water when you see a shark). Some fish have two dorsal fins one directly behind the other.
  
• endemic - Restricted to a particular place. Means the animal lives in a certain place and nowhere else.
  
• gonopodium - Particular to the Live-bearing toothcarps, the gonopodium is the pelvic fins of male fish that have been converted into genital organs.
  
• herbivore - Animals whose diet consists mainly of vegetable matter.
  
• hermatypic - Refers organisms that contain zooxanthellae. This usually means they need strong light to thrive.
  
• hermaphrodite - Refers to both male and female in the same organism.
  
• invertebrate - Animals that have no backbone.
  
• kalkwasser - German word meaning calcium water, kalkwasser is a mixture of calcium hydroxide in water. The ph is very high (around 12.0) and it is used as makeup water to replace calcium used by hard corals and clams to build calcerous skeletons.
  
• littoral - Pertaining to the edge of the lake, near the shore.
  
• mimicry - When an animal mimics, or copies the appearance of another animal in order to gain an advantage, like camoflage or a better defense. A good example is the marine fish, Mimic tang.
  
• nematocysts - The cells at the tip of an anemones' (corals) tenacles which "sting" when touched.
  
• omnivore - Animals who eat both meat and vegetables like marine angelfish.
  
• oviparous - Producing eggs which are fertilized, develop and hatch outside the body.
  
• ovoviviparous - Producing eggs (usually with yolk) that are fertilized internally. Hatching may occur internally or external to the mother.
  
• pinnate - Feather like. The 'pinnules' which are found on many octocorals are small side branches of the polyp tentacle which give it a 'pinnate' appearance.
  
• pelagic - Refers to living in the water of the ocean above the bottom. Pelagic organisms have the ability to swim around or move in some fashion. Benthos and benthic refers to living on or under substrate at the bottom of the ocean. Sessile means the organism is attached to the substrate.
  
• photosynthetic - The process by which organisms, usually plants, use the energy contained in light, usually sunlight.
  
• plankton - Plankton are the drifters of the sea. Although they may have some form of locomotion they are mostly carried by water currents. Plankton is divided into macroplankton (jellyfish, sargassum weed) and microplankton, organisms that can only be seen by a microscope. The microplankton is divided into zooplankton, tiny marine animals, and phytoplankton, or plants. Most fish start their lives as small animals in the plankton.
  
• predaceous - This means the animal will hunt and eat other animals. The old rule comes to mind, big fish eat little fish!
  
• sessile - Sessile means the organism is attached to the substrate at the bottom of the ocean and therefore cannot move around. Pelagic refers to living in the water of the ocean above the bottom. Pelagic organisms have the ability to move around. Benthos and benthic refers to living near or under substrate at the bottom of the ocean.
  
• symbiotic - A relationship where two or more different kinds of animals live together and both benefit in some way from the other's company. The most famous example is the clownfish and the anemone.
  
• sweeper tenacle/polyp - A coral tenacle or polyp that has an increased number of nematocysts and elongates in order to 'sting' neighboring corals and sessile invertebrates. See the Frogspawn coral, Euphyllia divisa for a picture of sweeper tentacles.
  
• Webers apparatus - described in 1820 by E. H. Weber, the Webers apparatus connects the hearing organ with the swim bladder where it operates as a sounding board thus amplifying sounds.
  
• zooplankton - see plankton.
  
• zooxanthellae - (zo-zan-thel-ee) The marine algae which lives in a symbiotic relationship with certain anemones and corals. The zooxanthellae are photosynthetic and require light. The host is nourished by the zooxanthellae byproducts.