Last Updated: 7/2/10
This page is to eventually include information on animal descriptions (size, color, shape, etc.), location of wild specimens, where one could buy the animal if applicable, what the animal eats and who eats it, its reproduction if known, benefits and down sides to having the creature around, hardiness, links, and more. My job with no time off precludes my finishing this page at this time but there is still a lot of information here.
These animals are species found near Maryland (native and introduced) but many have wide ranges all over the continent and even the world.
Reptiles - turtles and snakes
Amphibians - frogs, toads, salamanders, and newts
Other Arthropods - spiders, mites, shrimp, crayfish
Mollusks - snails and clams
Miscellaneous - sponges, hydra, jellyfish, moss animals
Only a rare cat will get into your pond but they will often fish by the edge. If the water is far enough below the rim, they cannot catch anything. Otherwise and in any case, provide lots of plants and things in which fish can hide.
Water loving dogs may jump into ponds, messing up plants and popping holes in the liner. If a neighbor refuses to contain his dog (which is the law in most areas) or your pooch just will not listen, you will have to fence in the pond.
An occasional opossum may decide to try a fishy snack but I have yet to hear a complaint on the newsgroup (rec.ponds) or the internet.
Raccoons love to eat fish. If you wake one morning to find plants knocked over and fish parts lying about, a raccoon may be the culprit. Raccoons like to be able to walk into the water. If the water is a drop off from the edge, they are less likely to get in the water. Ramps are open invitations.
Yes, I said humans. Hopefully, most visitors are invited or harmless trespassers who want a peek at your pond. Some, however, may decide to vandalize your pond. This can be very sad and discouraging. Security equipment may be necessary. Even friendly visitors may trip in for an unexpected swim. If you are in a populated area, it would probably be good to fence the pond in so that no one falls in the pond. In some areas, they can sue you even though they were trespassing. Also, if lots of young children are around, fencing may be necessary. Be sure that your visitors and neighbors who can see the pond know to stay off the rocks or edge of the pond and other pond rules you may have. Unless it is your intention (for a business or you are real proud of your work), it is best to situate your pond where as few passersby or neighbors can see it.
To attract songbirds and other small birds to your pond to drink and bathe, have a shallow area that they can walk into. A gradual depth from 0-3 inches with a flat area of about 2 inches is good. To discourage this behavior (so as to keep their feces out of your pond for example), create such a small pond away from the main pond. Also, if the pond has no way for birds to walk into a shallow area, they probably will not use it. As you can see on my main pond page, my 1800 gallon pond with cliff-like sides rarely sees birds while my 16 gallon pond attracts drinkers and bathers of all sorts.
Herons love to eat fish. They are most likely found at larger ponds with walk-in shallow areas up to about a foot deep. Reducing the walk-in areas, increasing the depth, and providing lots of plants and other hiding areas decrease the change of fish being eaten. Other strategies include fake herons (do not always work), scarecrow looking squirters which spray water on moving objects (must have water hookup there), and stringing high tensile wire about 6 inches off the ground around the pond. Because herons want to walk into a pond and apparently do not like to step over things, this last strategy seems to work for many people.
These cute little, look beaked birds may show up in sandy or muddy areas to peck around for bugs and other little critters. They rarely get in the water so pose little threat to ponds.
Large ponds are for ducks. Little water gardens or fish ponds are not places for ducks. Ducks will eat all the plants in a pond fast and leave feces all over. This creates havoc on the nitrogen cycle. Deterrents are similar to those for herons above. Ducks usually will only alight on ponds large enough for them to take off from (they need a running start). I love ducks, but not in my little pond.
Geese and ponds relate as ducks and ponds except that geese are bigger, eat more, and poop more. They also can be quite nasty. Nonetheless, they are among my favorite to have in very large ponds.
Swans are again like ducks and geese but yet even bigger. They are quite gorgeous though. If I ever had a large pond, I would love to have some.
These little turtles are very rare.
Common snapping turtle
Chelydra serpentina, or the snapping turtle, is often misjudged. Yes, it can bite; yes, it can eat fish; but no, it is not the end of your pond or getting in the pond. They only bite if you step on them or get to close. They will not come after you in most cases (each one is an individual as with most animals). Snapping turtles can eat fish almost as big as they are but probably will not eat too many. Set out a baited trap and relocate any turtles many miles away in more suitable habitat if your pond is not large enough for them (>10,000 gallons or so?).
Chrysemys picta is the painted turtle which grows to 5-6 inches. These are ideal turtles to use if you want to set up a turtle pond. They eat aquatic plants and fish. If your pond is large (>5000 gallons or so?), then you can add a few, and they will not decimate the plants and fish. Otherwise, you can give them their own pond with an enclosure around it. If some show up on their own that you do not want, try to nab them when they sun on rocks during the day and relocate them.
Clemmys guttata is the increasingly rare spotted turtle. They are gorgeous, small black turtles with yellow spots. These diminutive turtles only grow 3 to 5 inches long.
Clemmys insculpta is a rare turtle too.
Common water snake
Nerodia sipedon is a harmless (to you), quick, up to 3 feet long snake. They will eat whatever aquatic critters they can catch.
Eastern ribbon snake
Thamnophis sirtalis is the common garter snake but there are almost a dozen species of garter snake growing from 1.5 to 3 feet long. They are very opportunistic, eating whatever is available. Some are semi-aquatic. They are harmless to large mammals.
Rana catesbeiana is the largest frog in the United States. They are often suggested to add to ponds because they eat algae. Yes, the tadpoles eat algae for two years but the adults eat whatever they can fit in their large mouths! That means, you may notice tadpoles, frogs, fish, etc. vanishing. I would not suggest these frogs for small fish ponds. Bullfrogs can grow to 8 inches long. The males call is a deep "jug-a-rum." I did not add any to my pond but they have shown up. They are twice as big as the green frogs and look very fat. I wonder who they ate?
Hyla versicolor is the loud gray treefrog. From late spring to late summer, the males come out of the trees to sing like crazy. They are very loud. When females show up (many fewer of them), they lay small circular jelly-like masses of eggs. Most get eaten. Some change to frogs in a few months and head for the trees.
Rana clamitans is the common green frog. These frogs are like mini versions of bullfrogs that only grow to about 3 inches. Tadpoles change to frogs within one season. The males sing with a banjo twang. Tadpoles eat algae and plants. Adults eat mostly insects but other small animals as well. When they get too cold, green frogs turn black (mine did anyway). Males sound like a banjo twang. Here is a photo of one of my green frogs (arrow pointing towards him) surrounded by toad tapoles on 4/12/98. Green frog on lily pad, 5/16/98.
Northern leopard frog
Rana pipiens is one of the most common frogs. They come to water to breed but otherwise spend quite a large percentage of time away from water. I added two adults. One was sunbathing on a rock sticking out of the water a few weeks later so they may hang around water if it suits them.
Northern chorus frog
Northern cricket frog
Rana palustris, or the pickerel frog, is an interesting frog. It sort of looks like a leopard frog. They stay around water all year round and eat insects. I have found pickerel frogs to be less skiddish than other frogs; you can almost pet one. They grow to about 3 inches.
Hyla crucifer signals spring is near. They start cheeping at night during February or March and continue for a few months. These small tree frogs (1.5 inches) are rarely seen but you can sure hear them! They are only the size of your thumb nail but louder than any other wildlife!
Rana sylvatica is a frog that only spends time around water during breeding. I bought a few tadpoles to add to the pond. I believe I have seen at least one adult that survived. They are brown, cute, and skiddish.
The American toad is the color of dirt with "warts" and generally blends in well with dirt and rocks. Males grow to about 2 inches and females to about 4 inches. Bufo americanus loves to visit ponds in the spring to lay a trillion eggs. They are attached in long strings around plants. The large female and active male can stay joined for hours and submerge for long periods of time to avoid predators. During the night, males give off very loud trills to attract females but they tend to clasp together throughout the following day. Like their parents, the tadpoles are distasteful and perhaps poisonous. Fish and other predators avoid eating them. There are supposedly cases where fish did eat them and died but I have yet to see such a thing in my ponds. In April, hundreds of "toadpoles" swim around eating algae so I think that is good! Here is a photo of two mating toads (left arrow) and the strings of eggs all over the pots (right arrow), taken 5/22/97 when the pond was still new enough that the water was clear. This is a photo of lots of toad tadpoles swimming around and a green frog on the left (arrow), taken 4/12/98.
See the book referenced below for basically all that I know about these species.
Salamanders that are aquatic throughout their lives
Sirens (siren species), mudpuppies (Necturus maculosus), and hellbenders (Cryptobranchus alleganiensis) are three species of salamander that spend all of their lives in the water. They grow one to two feet long and eat fish, crayfish, insects, and whatever else they can get. They are "ugly" to blend in with their habitat so prey cannot see them. Due to their size, eating habits, and varying rarity in the wild, they are not species you would intentionally add to your pond but they could show up if you have wild waters that enter your pond, etc. A bird could also drop their eggs in your pond. It is weird how things show up that seemingly have no way of getting there.
Eastern newt or Red-spotted newt
Notophthalmus viridescens spends two stages of its life in the water. The newt is born in the water, turns into an eft and lives on land, and then returns to spend the rest of its life in water as it breeds. It grow 3 to 4 inches long and eats small animals. Efts are red while adults are a mix or greens, yellows, and reds.
The dusky salamander, or Desmognathus fuscus, is brownish and lives in the Eastern United States. Growing from 3 to 5 inches long, it must stay near water. Unlike most land salamanders, it lacks lungs and breathes through its skin so it must stay wet.
Pseudotriton montanus is the mud salamander. It lives in cool, wet mud and grows 3 to 5 inches long. Its color is brown.
The red-backed salamander, or Plethodon cinereus, lives in moist places and grows to 4 inches. It has a red stripe down its back and is black elsewhere.
Ambystoma maculatum is the only salamander species with which I have experience. I bought a few egg masses which hatched. All but 5 larvae went into my ponds to live. Five were raised to adulthood. They lost their gills and changed from brown to black with yellow splotches. They ate baby brine shrimp and cut-up black worms like little vacuum cleaners. I released the remaining 5 in May, 1998. Adults have a mass migration to breeding pools in late winter. The rest of the time, they are half a foot underground or under moist humus or leaves. Adults can grow to 7 inches long but tend to stay smaller. They feed on whatever comes their way that is small enough and slow enough to catch.
Ambystoma tigrinum is a rather large salamander that spends most of its life underground.
Eurycea bislineata hides in wet spots during the day and comes out at night to eat insects, worms, etc. like most salamanders. It has two yellowish lines down its brown back and only grows to about 3 inches.
Goldfish, koi, mosquito fish (gambusia), golden orfes, rosy red minnows, and fathead minnows are on this page .
Bitterlings are interesting in that they breed using mussels. Rhodeus amarus and Rhodeus sericeus are two Latin names used for this 4 inch species. They have long breeding tubes which they put into the mussel to lay eggs. If you have these fish, you need mussels (sometimes called clams). Unfortunately, mussels are often a necessity for some parasites to complete their life cycles too. Bitterlings are naturally colored, and they have tall bodies with pointy snouts.
Most North American catfish grow very large and eat whatever they can fit in their mouths. So, they are only suitable for huge ponds or ones without populations of smaller fish that you want to all survive. They require small fish like minnows and goldfish and other small animals to survive. Bullheads (Ictalurus species) and channel catfish (Ictalurus punctatus) are two groups of catfish that are most often encountered. Channel catfish are sold as pets in many colors even though they grow to about 4 pounds and have voracious appetites.
I have seen one species of fish referred to as the rainbow dace, red shiner, and minnow but it is all the same species. Some dace are minnows like the redbelly dace (Chrosomus eos) which is a nice addition to a pond. My book says that goldfish and koi are minnows too!
Darters are small fish that are becoming increasingly rare. The 100 or so North American species tend to live in streams and grow to about an inch, with some growing up to 5 inches. Males often build and guard nests. One species is the Johnny Darter or Etheostoma nigrum. These species should have a stream in which to swim.
Grass carp or Ctenopharyngodon idella grow up to 4 feet long. The wild colored grass carp will hardly be seen in a pond but new albino grass carp may work well in large ponds. They eat algae and plants. Because it is hardy, care must be taken to keep in out of wild waterways where it will eat native vegetation. They make good companions for koi.
Shiners are similar to minnows. Two North American species are the yellow shiner or Notemigonus crysoleucas and the redfin shiner or Notropis umbratilis. The first grows to a foot long but the second grows to 3 inches long, like most shiners and minnows. The terms shiner, dace, and minnow are often used interchangeably. Most species are compatible with goldfish and koi and make interesting additions to ponds. They are hard to find to buy. If it is legal in your area, you can capture some native fish but a two week quarantine is a must.
There are many species of minnow. The terms shiner, dace, and minnow are often used to describe the same fish. Most minnows grow to only a few inches, live near the surface of streams, eat insects, and pose no threat to other fish. I have a lot of info on the fathead and rosy red minnows at my fish page .
I heard or read somewhere that these were good pond fish but cannot find a source on them.
Rudd or Scardinus erythrophthalmus are interesting additions to ponds. They come in wild and man-made golden colors. They cruise the surface but at a slower speed than golden orfe. This is one species of fish I would like to acquire for my ponds but have yet to find a source.
The red shiner or horse-head minnow is a native of the US. They only grow to a few inches and are a good addition to a wild pond. Their Latin name is Cyprinella lutrensis.
Sunfish can be added to larger ponds but can grow to a foot or so, depending on the species. They are fat bodied so a foot is pretty big. They also will eat smaller fish in the pond but feed mostly on insects and crustaceans. Some species include the green sunfish (Lepomis cyanellus, 4 to 6 inches), the bluegill (Lepomis macrochirus, 8 to 12 inches), the pumpkinseed (Lepomis gibbosus, up to 10 inches), the warmouth (Chaenobryttus gulosus, 8 to 10 inches), and the orangespotted sunfish (Lepomis humilis, 4 to 5 inches). At least the first three species can hybridize (breed).
The tench or Tinca tinca comes in two varieties. The green tench is the wild type while the golden tench is a man-made variety. Red and red-and-white specimens show up from time to time. Tench are bottom feeders who stir up debris and may thus cloud the water. Most grow to about 15 inches but lengths of up to 28 inches are possible.
Megaloptera include alderflies, Dobson flies, and fishflies. These larvae are all predators. Their appendages are small but there are a LOT of them. Most are nocturnal. Alderfly larvae have thick brown skin, grow to about an inch long, have a single pointy tail, and tend to hide out. Dobson fly larvae are called hellgrammites (they look like they are from hell?) and grow up to 3 inches long. Fishfly larvae look like Dobson fly larvae, but only grow 1-2 inches long.
Coleoptera, or beetles, have a few species with aquatic larvae which are very predatory. Diving
beetles and whirligigs are common adult beetles which stick around the pond. Because there are
280,000+ species of beetle, most people know what an adult beetle looks like. Few people,
however, would identify dry-land worm-like creatures or what look like aquatic centipedes as
beetle larvae. Most beetle larvae can be identified separately from other insects because their
body is often covered in a much thicker, black plating and some species have long filaments off
the sides of their bodies. One species of larvae looks like a caddisfly larvae with a suit of armor.
Most range from .3 to 1 inch long but there is a large range. Likewise, their food preferences
vary from plant to animal to detritus. Some kinds of water beetles follow.
Crawling water beetles crawl around eating plants as larvae but adults eat animals too. Most of the 50 North American species range from .2 to .4 inches long. The larvae usually look like aquatic centipedes with very long filaments.
Predaceous diving beetles can be found both as larvae and adults in ponds. These 1 inch predators eat small insects and other animals. There are at least 300 species in North America alone. Adults spend a lot of time flying around to and show up at night lights.
Whirligig beetles are some of the funniest insects to show up at my ponds. The adults act like they have had too much too drink and spin around in the water. The .5 to 1 inch adults are scavengers and can see above and below water at the same time. Their front legs are long. The larvae, on the other hand, eat whatever animals they can catch and have more noticeable filaments than legs.
Trichoptera are some of the most common species you will find in your pond. Turn over a rock in your waterfall or stream. If there are worm like critters wiggling about or creatures inside little homes made of rock and debris, they are caddisflies. They use two tail hooks to anchor to their homes of leaves, sand, twigs, and other debris.
Odonata is the order containing the very visible dragonflies and damselflies which frequent
ponds. Because they eat lots of mosquitoes as adults, they are also called Mosquito Hawks.
These are large insects, growing 2 to 3 inches with 2 to 4 inch wingspans. Damselflies
differ from dragonflies in that they are smaller and very slender. Also, when resting, dragonflies
keep their wings open and damselflies keep theirs along their backs. Adults fly around and hang
out around ponds. A male and female often fly around and sit together while attached during
mating. Females lay eggs in the stems of water plants (they cut holes in the stems) throughout
After hatching, the nymphs stay in the water for three months to five years, depending on species. While there, they eat whatever they can catch and are thus known to some as menaces to ponds (whereas adults are a blessing, eating mosquitoes). Nymphs whole heartedly consume insects, worms, fry, small fish, tadpoles, frogs, and more. Hiding in mud, among rocks, and other places; they wait for prey to come near and then pounce. Ponds with lots of nymphs rarely have fry that survive to adulthood. I saw one two inch nymph with a three inch frog clasped in its fierce jaws. I freed the frog who otherwise (and may still have) would have been eaten.
If you wish to control these predators, you have to hand pick them out of the water. Also, large fish will eat them (but also small fish usually). The nymphs are camouflaged and look like adults except they are brown, have massive jaws, lack wings, and usually are less slender in the rear. Damselfly nymphs are more slender and have three gills on their rear, unlike dragonfly nymphs. Adults, aside from females laying eggs, pose no threat and bring the pond area alive. Often, ponders only realize that they had nymphs in their pond when they discover the cast off outer skins that nymphs leave behind when they leave the water as adults. The green darners (Anax) are the most common species of dragonfly with belted skimmers (Macromia) also being common. Common bluets are common damselflies. About 400 species of dragonflies and damselflies live in North America.
Diptera is a huge order. Here are some of the species or groups of species most frequently encountered.
Black flies can be identified by their large rear ends.
If you find a large 2-3 inch, fat, worm-like beast with tentacles on one end, you have found a crane fly larvae!
I discovered drone flies in my tiny pond shown at the top of this page. They are readily identified by their long breathing tubes which look like a long string (1-2 inches) attached to their rear. They keep the tubes sticking out of the water to breath. Their bodies look like land maggots (the kind that make many female humans scream). They are only found in shallow water without predators (fishless ponds). They writhe from plants to pond bottom and back in my pond. Unlike other flies, these flies do not sting, bite, or otherwise cause problems for humans. In fact, adults look like honey bees and pollinate flowers. My batch was in the pond from about late September to mid-November. They were hardy, surviving a number of shallow freezes.
Most often, people want to know about mosquito control so I will mention that now and add other information later. Female mosquitos bite mammals and birds and feed on their blood to nourish their eggs. She lays a raft of tiny eggs in still water which hatch into wriggling larvae. After a few weeks, these leave the water as adults. You can control mosquitoes one of two ways. First, add small insect-eating fish like young goldfish, fathead minnows, mosquito fish, etc. (see here for information of these fish). If you prefer a fish-less pond or one with large fish like koi who will not keep mosquito larvae under control, then you can add what are called mosquito dunks. These contain natural organisms which attack mosquito and similar larvae but will not harm non-insect animals or plants in any way. They can be ordered through many of the catalogs which I list at the bottom of my pond page. Also, increasing water movement and depth deters mosquitoes.
Phantom Crane Flies
Ephemeroptera, or mayflies, are very common. About 500 species occur in North America
alone. Mayflies are a vital source of food for higher animals, including your pet fish. They
range from .8 inches for the smaller species to 2.5 inches for the biggest species. Most ponds
have them in the bottom mulm or sludge. When I clean my bags of bioballs, they crawl out in an
attempt to find water again. They can be discerned from stoneflies and other insects by their
three tails which vary in length and adornment with species. Adults have four see-through wings
held aloft while resting. Three (or rarely two) long filaments extend from their abdomen in both
larvae and adults. Larvae are called naiads and have rows of leaflike gills down the sides of their
bodies. They eat small plants, animals, and debris for the two months to three years that they
spend in the water (varies with species). When the larvae are ready to leave the water, they pop
to the surface, shed their skin, and fly off. You may find their shed skins or exoskeletons around
the pond edges. After a few days dully colored (called a dun or subimago), they again shed to
become a shiny, breeding adult (called a spinner or imago). They are called Ephemeroptera
because the mature adults are ephemeral, meaning they die after just a few hours (but not before
they breed and females lay eggs in water). Since they live so short a time as adults, their mouths
are non-functional, and adults do not eat. Sometimes a swarm of millions of adults will mate in
Some types of mayflies include hexagenias (largest in North America), isonychia (dart about in fast water), cloeon (climbs around plants), ephemerella (common, big gills, clings to things), ephemera (live in sediment, move gills to get oxygen in the borrow), and blasturus (in early Spring, dart around).
Lepidoptera, or moths, contains a few species whose larvae are aquatic.
Neuroptera or spongilla flies are small and active larvae with bristles on their body. They eat freshwater sponges (thus "spong"illa). The six or so species in North America are not well studied at all.
Collembola are common in the spring. They are white, tiny, and bounce all over the pond surface. They do no harm and small animals may eat them. Less than .2 inches long, they use a forked tail to spring about. They do not enter the water.
Plecoptera, or stoneflies, are indicative of good water quality. They are similar in appearance to mayflies but generally larger and with only two tails. About 300 species can be found in North America. Nymphs prefer flowing water. Growing from .8 to 2 inches, they have tufts of gills under their legs (like arm pit hair). Some species eat animals while others eat plants. They look like aliens to me.
Hemiptera include the common water striders, water boatmen, backswimmers, water scorpions,
and water bugs. All of these stay around the pond as adults as well, eating small animals,
insects, and fish. I find water boatmen to be cute. On the other hand, their mouths are made to
pierce and suck which does not sound too pleasing. True bugs are good swimmers and clingers
and prefer to eat insects. Some species follow.
Backswimmers are similar to water boatmen but they swim on their backs and only grow to about .5 inches. They store air under their bodies. North America has about 20 species. Look but do not touch them; their bite is painful.
The broad-shouldered water striders include the genuses Microvelia and Rhagovelia (which has hairy tufts on its legs for paddles). The 20 or so North American species catch small creatures on the surface and grow up to .5 inches.
Creeping water bugs also carry air, under their wings. These .3 inch bugs have strong legs and move through the water slowly, unlike water boatmen and backswimmers who just fly!
The largest true bugs of all are the giant water bugs , growing up to 3 inches. Their poisonous bite can kill small fish, tadpoles, and insects easily. Of the 24 species, some species practice male brood care where the male carries the eggs along his back even though they weigh a lot.
The marsh treader or water measurer is a slender, stick-like stalker that hides among thick plants. They spear prey with a beak and suck out the body fluids. There are six species known in North America. Hydrometra martini is a species that grows to about .5 inches.
One species of pygmy backswimmer , Plea striola, lives in North America. It grows to .1 inches and swims between patches of plants eating small crustaceans. It looks a little like a flea.
Water boatmen are common. They are often seen swimming in the water column in ponds and swimming pools. Water boatmen look like a submerged canoe with two men paddling. They may have a pocket of air around their 1 inch bodies. They eat algae and detritus. Of the 115 or so species, two common genera are Arctocorixa and Corixa.
Water scorpions are nasty looking insects. Hiding underwater with a snorkel or breathing tube, they seize passing prey with strong legs and kill it. Since they grow up to 2.5 inches, finding one of these skinny, stick-like insects with large pincher legs often sends ponders into a panic. Yes, all 12 North American species do eat small fish.
Likewise, the ordinary water striders or water skaters catch prey on the surface. Growing up to an inch, the 30 or so species often congregate on the surface of ponds where they zip around the surface. Gerris marginatus is one species which grows to about .8 inches.
Three species of water treaders live in North America. An example is Mesovelia mulsanti which grows to .5 inches. They are green and live concealed on the surface and eat small animals.
Finally, there are .3 inch toad and shore bugs who live near water and tend to go for dead bugs.
Clam shrimp (conchostraca) are interesting little shrimp that look like .5 inch clams. They prefer warm, shallow waters.
Fairy shrimp or anostraca show up occasionally in ponds or can be bought. They swim with their many appendages waving above them, as if they are doing the back float. There are about 25 species, including the very well known brine shrimp which prefers brackish water. Most species can produce either live young or leave eggs, which upon drying completely, hatch when again wet. These species are often used to feed fish. Maximum lengths are less than an inch.
Ghost (glass, grass, etc.) shrimp
These freshwater shrimp are often sold as "feeders" for all sorts of aquatic life. I have found that they live in ponds at least as low as the 50's degrees F. They probably will not survive the winter (I have yet to find out); plus, their life spans are not that long. I have also yet to find out if they breed in ponds. Females carry eggs but in aquaria, the tiny newborns always get eaten.
Scuds (amphipoda) are not true shrimp. These creatures grow to half an inch and look a little like fleas. They swim on their sides and eat plant and animal debris. Gammarus and Hyalella are two kinds. Scuds avoid light and fish like to eat them. A bad side is that they are often intermediate hosts for tapeworms and other parasites of larger animals like fish and frogs. They like lightly brackish water.
Seed shrimp or ostracoda only grow to .1 inch in size. They look like clams and often have pretty colors. Some 150 species scavenge the algae and mud in North American ponds. Some species lack males; females lay unfertilized eggs which hatch and grow.
The tadpole shrimp is a unique predator. Like salt water brine shrimp, they only breed in temporary waters. The eggs must dry up completely and then re-wet to hatch. They look like extinct trilobites except they are only about an inch long at full size. They will eat anything they can catch, no matter the size. They especially like to eat each other. It is a wonder that they ever breed! You can buy them at some pet stores and through some catalogs. They sure look funny in a pond, zipping around very fast. Mine was the king of the pond for a month. They only live two months or so.
Crayfish and prawns can be added to ponds as scavengers. Although they mostly eat plants, they will keep extra fry in check by eating them too. Growing up to five inches, these species will also eat dead fish and other animals. More than 200 species of these crustaceans make various habitats in North America their home.
There are a number of species of earthworms or oligochaeta. Tubifex are inch-long, red, and live in tubes in bottom mud. Chaetogasters eat small animals with their large mouths and grow to half an inch. Deros build tubes in debris, grow to about half an inch, and have bristles. Aeolosomas grow to half an inch, live in debris or on plants, and can have colorful spots. All species tend to stay on the bottom or in debris, dirt, etc.
Leeches prefer shallow, slow moving, warm water with lots of detritus. Some are scavengers, some hunt small animals, and others suck blood. Sizes range from a few inches to almost two feet! Some species of leeches, or hirudinea, include helobdellas, erpobdellas, macrobdellas, and haemopsis. Colors and sizes range but all are flat and segmented. If your pond develops an overabundance of fish or people sucking leeches, you can place a piece of raw beef or other bloody meat in the pond on a string. Remove later, and it should now be covered in leeches.
Flatworms or platyhelminthes include flukes, tapeworms, and turbellarians. The first two are familiar parasites. The latter move around on surfaces using cilia and eat small living or dead animals. Planaria, a common turbellarian, often over-reproduce in aquaria but I do not think they are a problem in ponds. Other turbellarians are also rather harmless. Dugesias tigrina is the largest free-living flatworm, growing to an inch long.
First a note on snail reproduction: Most snails are hermaphrodites. This means that they are both male and female. All can lay eggs. They can "mate" with themselves and thus only one can reproduce. They also breed sexually as often as possible. Most snails lay eggs but some give live birth.
Four horned snail
The four horned snail or ampullaris cuprina is a large, semi-tropical snail. It lays 200-300 hard yellow to orange eggs above water throughout summer and fall. They have a ravenous appetite and in my pond, include many of my water plants. However, their damage is minimal and they seem to prefer eating detached pieces of vegetation. They can grow to a few inches in diameter. I have yet to see if they can survive a winter here.
Golden Inca snails
Golden Inca snails are very similar to the above four horned snails but have more gold. Since their Latin name is ampullaris cuprina aurea, they may interbreed with four horned snails. They look like larger four horned snails.
There are three different reactions to these snails. One, they are horrible and will destroy all plants and pollute the water and must die at any cost. Two, they are natural and part of the system and let us leave them alone. Three, they are great assets because they eat some algae. Well, they do eat plants but fish and other animals eat them in return too. Thus, I think that you should treat plants to kill snails before adding them BUT, when they show up anyway (they will!!), just let them be and do their part. Pond snails are hermaphroditic egg-layers that breed very fast.
These horn-shaped snails clean algae off surfaces and grow to about an inch. They are good to have around. They are hermaphroditic egg-layers. One species is planoribis rubrum.
The Japanese trapdoor snail's Latin name is viviparis malleatus; viviparis means they give live birth. Trapdoors are large (1-2 inch) snails shaped like a swirly ball. They eat algae and plants. Trapdoors are live-bearers and thus breed more slowly than other snails. In my pond, most died for no reason.
Trumpet snails are shaped like a cornucopia. They are egg-layers who live in the substrate. They are often said to be good because they move the substrate around and aerate it. They can reproduce quickly sometimes.
Clams or Mussels are best utilized in large, older ponds to sift algae and other floating life from the water. Place them in a tray of sandy dirt in the bottom. Remove dead ones often so as not to pollute the water. They die if there is not enough food. Their larvae often parasitize the gills of fish and in large numbers, may harm fish.
Cyclops are copepods often sold as fish food. These small crustaceans (.1 inch) eat algae, bacteria, debris and a few species are harmless parasites of fish. Females carry eat sacks which make them easy to identify. They look somewhat like terrestrial sowbugs (isopods, a few species live in water eating rotting plants). The three groups of free-living copepods are calanoid, cyclopoid (the only real cyclops), and harpacticoid.
Daphnia (also called water fleas and cladocera) are often sold as fish food (daphnia magna and daphnia pulex specifically). These crustaceans eat algae and microorganisms. They wave their legs around while swimming with jerking motions to bring food to their mouths. They tend to hang out with the plankton and many animals eat them. They are one of the essential species for a healthy pond in many areas since they eat algae and in turn feed the fish. Looking somewhat like terrestrial fleas, they grow up to .1 inch with females giving live birth to tiny babies fit for fish fry to eat.
There are nearly 2,000 species of rotifers which differ in their appearance and lifestyles. Some swim, some crawl, some stick onto surfaces using a sort of glue but they all are multi-celled tiny animals with cilia which they use for locomotion and food retrieval. Some eat plants, some algae, some other small animals but all are important foods for larger animals. A few species can survive their water being completely dried out.
Hydra or Coelenterata look like small bags with tentacles. Growing to about an inch long, they eat whatever they can catch, mostly microorganisms. Their tentacles either stick to or sting their prey. In aquaria, they are the scourge of fry tanks; fry being a favorite food. While they tend to stay attached to some surface, they can move around to find better spots. The brown, green (contains algae), and American hydra are species common to North America.
There is only one species of freshwater jellyfish in North America, Craspedacusta sowerbyi. It goes through life stages including one similar to the hydra and growing to only about a half inch to look like the more common marine species.
Similar to sponges, but with tentacles, moss animals or bryozoans are strange creatures. About 15 species occur in North American fresh waters. They grow in still, clean water. Many thousands of individuals may encrust onto rocks, pipes, etc.
There is only one family of fresh water sponges or Porifera. About 150 species live in ponds and lakes throughout the world. Larvae are free swimming but adults are brown or greenish globs from an inch to a dozen square feet in size. Green sponges have symbiotic algae. They eat microorganisms that get sucked in through their pores. A single sponge is actually a colony of animals like coral. In cold areas, sponges may drop gemmules which survive the winter on the bottom of the pond with the "parent" dying.
Familiar Reptiles & Amphibians of North America, National Audobon Society Pocket Guide, Alfred A. Knopf, 1996.
National Audobon Society Field Guide to North American Insects & Spiders, Alfred A. Knopf, 1997.
Pond Life: A Guide to Common Plants and Animals of North American Ponds and Lakes by Dr. George K. Reid, Golden Press, 1967. A book chock full of information.
Newts and Salamanders by Frank Indiviglio, Barron's, 1997.
1997-1998 Ponds and Watergardens USA Annual by various authors, Fancy Publications, Inc., 1997.
The Audobon Society Nature Guides: Wetlands by William A. Niering, Alfred A. Knopf, 1992.
+ Knowledge I have gained and stored in my brain.