What Is This Critter? Identification Guide for Various Freshwater Invertebrates

[Wy Renegade]

I came across a similar thread on another forum and absolutely love it, but I think AA needs its own. My idea is to get it started, and anyone can contribute. To start I'd like to keep it simple, staying at the level of order and then build in complexity from there. Maybe eventually adding some specific genuses or species which are common. At some point perhaps we can do a formal sticky thread out of everyone's posts in alphabetical order so that it becomes a handy guide for anyone to reference when they have a question about what a particular critter they find in their tank is. I am going to ask that if you contribute, please use only your own photos rather than one borrowed off the internet somewhere. I realize that may limit some of you, but it prevents copyright issues.

So to get us started, here's an example of the format I'd like to use . . .

 

[Wy Renegade]

Amphipoda

Order Amphipoda (Scuds, Sideswimmers);

Classification: Amphipods, frequently referred as "freshwater shrimp" are an order of crustaceans with 13 body segments and a variety of appendages which are found in all aquatic environments, as well as a few terrestrial ones. The majority of species are marine, with only about 90 American species described that are confined to freshwater.

Activity: They are generally more active during the night than during the day, and are typically confined to the substrate. They swim with a somewhat skittering locomotion with the animal on its side, flexing their appendages, hence the common name "sideswimmer."

Feeding: Voracious feeders, most amphipods are omniovorous detritivores or scavengers, feeding on all kinds of animal and plant matter as well as organic debris. Some few are grazers of algae or predators on small insects or other crustaceans.

Size: Typically less than 10mm, they range from 1mm to 28cm depending on species.

Aquarium Impact: Commonly employed in aquariums as a food source for fish or other organisms. Some also employ them as scavengers or a clean-up crew.

 

[Wy Renegade]

Annelida (Hirudinea)

Phylum Annelida, SubClass Hirudinea (Leeches);


(some where I have a picture, but couldn't find it tonight).

Classification: Leeches are annelids or segmented worms, with suckers on each end of their body, frequently referred to as "bloodsuckers." Predominantly freshwater, there are also marine and terrestrial species.

Activity: All leeches move on the substrate with a characteristic looping or inchworm movement, by gripping alternately with their suckers. Some are excellent swimmers, gliding through the water with graceful up-and-down or side-to-side undulations, others are poor swimmers and roll up like a pillbug, falling to the substrate when disturbed.

Feeding: Contrary to popular opinion most leeches are predators feeding on small invertebrates or scavengers feeding on organic debris, with only a small minority sucking blood from warm-blooded animals.

Size: Typically around an inch when contracted, they range from minute species on 5mm long to some giant species that are over 45cm when extended and swimming.

Aquarium Impact: Obviously bloodsucking varieties should be removed from the typical aquarium, however scavengers can actually benefit the community by removing organic debris.

 

[Wy Renegade]

Bivalvia

Class Bivalvia, Order Pelecypoda (The Mussels);

Classification: Class bivalvia are members of phylum mollusca that have two valves (or halves) to their calcium carbonate shell. The members of class bivalvia are all aquatic and the valves typically gape to allow the protrusion of a muscular foot and an incurrent and excurrent siphon. In some species the shell may be entirely submersed in the substrate with only the siphons appearing at the surface. Freshwater bivalves occur in all types of unpolluted habitats, but are most abundant and varied in the shallow regions of larger bodies of water.

Activity: Mussels move over and through the substrate by using their muscular foot in a series of short "hunching" movements, and some species can move as far as several feet per hour. Such treks can result in a long, troughlike track clearly visible through the substrate.

Feeding: Mussels are filter feeders, subsisting on a diet of zooplankton, phytoplankton, and organic debris.

Size: Adult size varies from 3 mm to 20 cm depending on species.

Aquarium Impact: Seldom kept in freshwater aquarium, mussels require a stable, well-balanced aquarium with excellent water quality and a large population of microorganisms. As filter feeders, they can contribute significantly to keeping populations of planktonic organisms under control. If their food supply runs out however, they can quickly starve.

 

[Wy Renegade]

Coleoptera

Order Coleoptera (The Beetles);

larval stage of aquatic beetle;

Adult Predaceous Diving Beetle;

Classification: Adult beetles are pretty familiar to most folks and are insects in the order coleoptera. Their latin name coleoptera, comes from the Greek "koleon" which means sheath and "ptera" which means wings, refers to their two pairs of wings, of which the outermost pair is hardened into a sheath like covering. By far the largest order of insects with more than 250,000 species most are terrestrial and only a few are wholly or partly aquatic.

Activity: Adult members of the aquatic species are generally more active at night and are found everywhere in streams, rivers, ponds, and protected bays; typically near the shore in large quantities of debris and aquatic vegetation. Some are good swimmers with their hind legs flattened and hairy, while others simply crawl about on the substrate. Adult forms are able to fly, and since almost all are oxygen dependent they carry a film of air with them when they are submerged which must be renewed at the surface in regular intervals. A few species have anal gills. Metamorphosis is complete and the larva form typically has well-developed legs and mandibular mouthparts. The pupal stage is almost always terrestrial, but adult aquatic species have aquatic larva, and the eggs are deposited below the waters surface.

Feeding: Food habits are variable by species, ranging from strictly predatory to a vegetarian diet.
Size: Size varies considerably depending on species with many common species being overlooked because of their small size, inconspicuous coloration and secretive habits. Some of the larger species become very visible when they are attracted to brights lights during the migratory night flights from one body of water to another.

Aquarium Impact: Since adult forms fly, adult beetles are seldom a viable option for long term aquarium placement. Some larval forms may accidently be imported on aquatic vegetation.

 

[Wy Renegade]

Copepoda

Subclass Copepoda (The copepods);

NO Picture at this Time

Classification: Copepodes ("oar-footed") are a group of small crustaceans found in the ocean and nearly every freshwater habitat worldwide. They are typically the dominant form of zooplankton and are found primarily in the plankton, benthic, and near shore regions of freshwater, and are seldom found in rapid waters. Freshwater copepods are found in only two of the 10 orders of copepods; Eucopepoda and branchiura.

Activity: Sometimes found in unbelievable numbers of almost 4,000 individuals in a gallon of water. Generally Copepods crawl across, run on or through the substrate, as well as swim by using their legs. Those that are parasitic are found on the bodies of their host.

Feeding: With so many different species, feeding habits vary greatly. Some are herbivorous, scraping algae and debris form the bottom, others are carnivorous and some few species are parasitic. Generally food consists of unicellular algae and protozoans, other smaller crustacians, and organic debris. Canibalism on immature stages is common.

Size: Typically less than 2.0mm in length, American species range from 0.3mm to 3.2mm.

Aquarium Impact: Commonly cultured and employed in aquariums as a food source for fish or other organisms. Copepod parasites are found on most common species of fish and are seldom present in sufficient numbers to cause serious injury to the host. In aquariums however, heavy and serious infections can break out. Once established copepod parasites are difficult to control, because the exoskeleton is resistant to chemical solutions. In extreme conditions there may be no alternative but to get rid of the parasitized fish, clean the aquarium and start again.

 

[Wy Renegade]

Decapoda

Order Decapoda (The Crayfish and Shrimp);

TBF

Classification: Amphipods, frequently referred as "freshwater shrimp" are an order of crustaceans with 13 body segments and a variety of appendages which are found in all aquatic environments, as well as a few terrestrial ones. The majority of species are marine, with only about 90 American species described that are confined to freshwater.

Activity: They are generally more active during the night than during the day, and are typically confined to the substrate. They swim with a somewhat skittering locomotion with the animal on its side, flexing their appendages, hence the common name "sideswimmer."

Feeding: Voracious feeders, most amphipods are omniovorous detritivores or scavengers, feeding on all kinds of animal and plant matter as well as organic debris. Some few are grazers of algae or predators on small insects or other crustaceans.

Size: Typically less than 10mm, they range from 1mm to 28cm depending on species.

Aquarium Impact: Commonly employed in aquariums as a food source for fish or other organisms. Some also employ them as scavengers or a clean-up crew.

Order Diptera (The True Flies);

TBF

Classification: Amphipods, frequently referred as "freshwater shrimp" are an order of crustaceans with 13 body segments and a variety of appendages which are found in all aquatic environments, as well as a few terrestrial ones. The majority of species are marine, with only about 90 American species described that are confined to freshwater.

Activity: They are generally more active during the night than during the day, and are typically confined to the substrate. They swim with a somewhat skittering locomotion with the animal on its side, flexing their appendages, hence the common name "sideswimmer."

Feeding: Voracious feeders, most amphipods are omniovorous detritivores or scavengers, feeding on all kinds of animal and plant matter as well as organic debris. Some few are grazers of algae or predators on small insects or other crustaceans.

Size: Typically less than 10mm, they range from 1mm to 28cm depending on species.

Aquarium Impact: Commonly employed in aquariums as a food source for fish or other organisms. Some also employ them as scavengers or a clean-up crew.

 

[Wy Renegade]

Ephemeroptera

Order Ephemeroptera (The Mayflies);

TBF

Classification: Amphipods, frequently referred as "freshwater shrimp" are an order of crustaceans with 13 body segments and a variety of appendages which are found in all aquatic environments, as well as a few terrestrial ones. The majority of species are marine, with only about 90 American species described that are confined to freshwater.

Activity: They are generally more active during the night than during the day, and are typically confined to the substrate. They swim with a somewhat skittering locomotion with the animal on its side, flexing their appendages, hence the common name "sideswimmer."

Feeding: Voracious feeders, most amphipods are omniovorous detritivores or scavengers, feeding on all kinds of animal and plant matter as well as organic debris. Some few are grazers of algae or predators on small insects or other crustaceans.

Size: Typically less than 10mm, they range from 1mm to 28cm depending on species.

Aquarium Impact: Commonly employed in aquariums as a food source for fish or other organisms. Some also employ them as scavengers or a clean-up crew.

 

[Wy Renegade]

Hydracarina

Order Hydracarina (The Hydras);

TBF

Classification: Amphipods, frequently referred as "freshwater shrimp" are an order of crustaceans with 13 body segments and a variety of appendages which are found in all aquatic environments, as well as a few terrestrial ones. The majority of species are marine, with only about 90 American species described that are confined to freshwater.

Activity: They are generally more active during the night than during the day, and are typically confined to the substrate. They swim with a somewhat skittering locomotion with the animal on its side, flexing their appendages, hence the common name "sideswimmer."

Feeding: Voracious feeders, most amphipods are omniovorous detritivores or scavengers, feeding on all kinds of animal and plant matter as well as organic debris. Some few are grazers of algae or predators on small insects or other crustaceans.

Size: Typically less than 10mm, they range from 1mm to 28cm depending on species.

Aquarium Impact: Commonly employed in aquariums as a food source for fish or other organisms. Some also employ them as scavengers or a clean-up crew.

 

[Wy Renegade]

Isopoda

Order Isopoda (The Isopods);

TBF

Classification: Amphipods, frequently referred as "freshwater shrimp" are an order of crustaceans with 13 body segments and a variety of appendages which are found in all aquatic environments, as well as a few terrestrial ones. The majority of species are marine, with only about 90 American species described that are confined to freshwater.

Activity: They are generally more active during the night than during the day, and are typically confined to the substrate. They swim with a somewhat skittering locomotion with the animal on its side, flexing their appendages, hence the common name "sideswimmer."

Feeding: Voracious feeders, most amphipods are omniovorous detritivores or scavengers, feeding on all kinds of animal and plant matter as well as organic debris. Some few are grazers of algae or predators on small insects or other crustaceans.

Size: Typically less than 10mm, they range from 1mm to 28cm depending on species.

Aquarium Impact: Commonly employed in aquariums as a food source for fish or other organisms. Some also employ them as scavengers or a clean-up crew.

 

[Wy Renegade]

Gastropoda

Order Gastropoda (The Snails and Slugs);

TBF

Classification: Amphipods, frequently referred as "freshwater shrimp" are an order of crustaceans with 13 body segments and a variety of appendages which are found in all aquatic environments, as well as a few terrestrial ones. The majority of species are marine, with only about 90 American species described that are confined to freshwater.

Activity: They are generally more active during the night than during the day, and are typically confined to the substrate. They swim with a somewhat skittering locomotion with the animal on its side, flexing their appendages, hence the common name "sideswimmer."

Feeding: Voracious feeders, most amphipods are omniovorous detritivores or scavengers, feeding on all kinds of animal and plant matter as well as organic debris. Some few are grazers of algae or predators on small insects or other crustaceans.

Size: Typically less than 10mm, they range from 1mm to 28cm depending on species.

Aquarium Impact: Commonly employed in aquariums as a food source for fish or other organisms. Some also employ them as scavengers or a clean-up crew.

 

[Wy Renegade]

Bivalvia

Order Bivalvia (The Mussels);

TBF

Classification: Amphipods, frequently referred as "freshwater shrimp" are an order of crustaceans with 13 body segments and a variety of appendages which are found in all aquatic environments, as well as a few terrestrial ones. The majority of species are marine, with only about 90 American species described that are confined to freshwater.

Activity: They are generally more active during the night than during the day, and are typically confined to the substrate. They swim with a somewhat skittering locomotion with the animal on its side, flexing their appendages, hence the common name "sideswimmer."

Feeding: Voracious feeders, most amphipods are omniovorous detritivores or scavengers, feeding on all kinds of animal and plant matter as well as organic debris. Some few are grazers of algae or predators on small insects or other crustaceans.

Size: Typically less than 10mm, they range from 1mm to 28cm depending on species.

Aquarium Impact: Commonly employed in aquariums as a food source for fish or other organisms. Some also employ them as scavengers or a clean-up crew.

 

[Wy Renegade]

Mysideacea

Order Mysidacea():
TBF

Classification: Amphipods, frequently referred as "freshwater shrimp" are an order of crustaceans with 13 body segments and a variety of appendages which are found in all aquatic environments, as well as a few terrestrial ones. The majority of species are marine, with only about 90 American species described that are confined to freshwater.

Activity: They are generally more active during the night than during the day, and are typically confined to the substrate. They swim with a somewhat skittering locomotion with the animal on its side, flexing their appendages, hence the common name "sideswimmer."

Feeding: Voracious feeders, most amphipods are omniovorous detritivores or scavengers, feeding on all kinds of animal and plant matter as well as organic debris. Some few are grazers of algae or predators on small insects or other crustaceans.

Size: Typically less than 10mm, they range from 1mm to 28cm depending on species.

Aquarium Impact: Commonly employed in aquariums as a food source for fish or other organisms. Some also employ them as scavengers or a clean-up crew.

 

[Wy Renegade]

Nematoda

Order Nematoda (The Flatworms);

TBF

Classification: Amphipods, frequently referred as "freshwater shrimp" are an order of crustaceans with 13 body segments and a variety of appendages which are found in all aquatic environments, as well as a few terrestrial ones. The majority of species are marine, with only about 90 American species described that are confined to freshwater.

Activity: They are generally more active during the night than during the day, and are typically confined to the substrate. They swim with a somewhat skittering locomotion with the animal on its side, flexing their appendages, hence the common name "sideswimmer."

Feeding: Voracious feeders, most amphipods are omniovorous detritivores or scavengers, feeding on all kinds of animal and plant matter as well as organic debris. Some few are grazers of algae or predators on small insects or other crustaceans.

Size: Typically less than 10mm, they range from 1mm to 28cm depending on species.

Aquarium Impact: Commonly employed in aquariums as a food source for fish or other organisms. Some also employ them as scavengers or a clean-up crew.

 

[Wy Renegade]

Odonata

Order Odonata (The Damsel and Dragonflies);

TBF

Classification: Amphipods, frequently referred as "freshwater shrimp" are an order of crustaceans with 13 body segments and a variety of appendages which are found in all aquatic environments, as well as a few terrestrial ones. The majority of species are marine, with only about 90 American species described that are confined to freshwater.

Activity: They are generally more active during the night than during the day, and are typically confined to the substrate. They swim with a somewhat skittering locomotion with the animal on its side, flexing their appendages, hence the common name "sideswimmer."

Feeding: Voracious feeders, most amphipods are omniovorous detritivores or scavengers, feeding on all kinds of animal and plant matter as well as organic debris. Some few are grazers of algae or predators on small insects or other crustaceans.

Size: Typically less than 10mm, they range from 1mm to 28cm depending on species.

Aquarium Impact: Commonly employed in aquariums as a food source for fish or other organisms. Some also employ them as scavengers or a clean-up crew.

 

[Wy Renegade]

Plecoptera

Order Plecoptera (The Stoneflies);

TBF

Classification: Amphipods, frequently referred as "freshwater shrimp" are an order of crustaceans with 13 body segments and a variety of appendages which are found in all aquatic environments, as well as a few terrestrial ones. The majority of species are marine, with only about 90 American species described that are confined to freshwater.

Activity: They are generally more active during the night than during the day, and are typically confined to the substrate. They swim with a somewhat skittering locomotion with the animal on its side, flexing their appendages, hence the common name "sideswimmer."

Feeding: Voracious feeders, most amphipods are omniovorous detritivores or scavengers, feeding on all kinds of animal and plant matter as well as organic debris. Some few are grazers of algae or predators on small insects or other crustaceans.

Size: Typically less than 10mm, they range from 1mm to 28cm depending on species.

Aquarium Impact: Commonly employed in aquariums as a food source for fish or other organisms. Some also employ them as scavengers or a clean-up crew.

 

[Wy Renegade]

Porifera

Porifera TBF

 

[Wy Renegade]

Protozoa

Protozoa TBF

 

[Wy Renegade]

Tricoptera

Tricoptera TBF

 

[Wy Renegade]

Just in case