Welcome to the Triops Information Page! Since I first designed this page (in 1997) the number of pages about Triops has gone up from ~10 to over 8,000! Clearly, there has been a dramatic increase in interest in these freshwater crustaceans! I have received many inquiries about these shrimp since they have been sold in various novelty stores (see side bar for various locations selling Triops, which are sometimes also called "Aquasaurs" or "Living Fossils"). Hopefully, this page will answer most of your questions regarding Triops, and in general pique your interest in these fascinating critters. If you are also interested in other similar crustaceans (the category of crustaceans which includes Triops is called "Branchiopods"), see my other pages on other types of branchiopods (especially clam shrimp). Also, an excellent video has been produced by Bullfrog Films, Inc. on branchiopods, which I highly recommend for those interested in these unique critters!
The tadpole shrimp (scientific name = Triops longicaudatus, which are in the order Notostraca in the class Branchiopoda) inhabits freshwater, ephemeral ponds ranging from 50ºN latitude in western North America through Central America and into South America. In the U.S., Triops are found in desert habitats (see Figure 1). They live in small pools that accumulate after flash floods in the summer. Since these pools are rather short-lived, the Triops consequently have short lifespans, completing their life cycles in a mere 20-40 days!
Fig. 1 - Triops habitat
Populations of Triops comprise males and hermaphrodites, with wide variation in the numbers of both sexual types. Most populations have many more hermaphrodites than males, and in some ponds, no males are found at all. The hermaphrodites can fertilize their own eggs (called "selfing"), or can mate with a male. The fertilized eggs are called "cysts" or "resting eggs," and can be dried for several years to decades before being hatching when rehydrated. In this cyst form, Triops can withstand extremes of heat and cold. (This is why they can be sold in plastic bags in novelty stores!) The eggs are carried by the hermaphrodites in small "brood pouches" located on two of their swimming appendages (about half-way down the length of the body, on the left and right sides). The eggs are either white or pinkish in color, and are carried in these pouches for between 12 and 24 hours before being laid in the ponds. (Note: some of the Triops actually cement their eggs on various structures (e.g., twigs, grass, etc.) in their ponds. If you drape something like a plastic or fiberglass mesh (like a small bit of a window screen) over the side of those small plastic containers that are included with kit, you might get the hermaphrodites to lay their eggs on the screen!)
Fig. 2 - A nauplius larvae
When the cysts are rehydrated, they split open releasing the developing embryo. The embryo quickly develops (within several hours) into a "nauplius" larval stage (See Figure 2), which is a filter feeding stage that swims in the water column. At this stage, the nauplii are attracted to a bright light, so if you hold a light bulb next to the container, the nauplii will swim toward the light. (Note: do not get the bulb too close to the plastic containers or it will melt!)
The Triops quickly molt (shed their exoskeleton exposing a larger exoskeleton underneath) through several naupliar stages, and finally molt into a juvenile Triops, which migrates to the bottom of the tank. At this stage, the juveniles have the general shape that they will retain throughout their life. The juveniles leave "tracks" in the soil (see Figure 3), which are little lines that are indicative of their "rooting" through the soil material (they are basically bottom-feeders).
Fig. 3 - Triops digging in the dirt
The Triops have two large mandibles that they use for grinding up both live and dead food items. (Note: although the mandibles are "large" from the Triops's perspective, they are quite small to humans. Thus, there is no danger that a Triops can bite a person!) They eat plants, other animals (e.g., other crustaceans, and sometimes even each other!), and dead material (called detritus). The Triops will be about ¼ inch (~ 5mm) in total length at this stage. They will quickly grow to adult size (1-1.5 inches or up to 40 mm) in about 2 weeks. (Note: Growth is strongly dependent on density, so the Triops in the small plastic containers included in the purchased kit may not get quite this big.) At this point, the hermaphrodites begin to produce eggs, producing about 1 batch (or "clutch") of eggs per day. The Triops continue to produce eggs until their death, which averages between 2 and 4 weeks of age. However, some can live quite a bit longer, as the Triops shown below (Fig. 4) that reached 100 days of age and got to be nearly 3 inches in length!
Figure 4 - Oldest living Triops recorded to date: 100 days (thanks to Maryanne McFalls and her son from Soddy-Daisy, TN for the information and picture of this "old gal"!)
Last Updated : 1/2/13
The Clam Shrimp Information Page - Information, movies and pictures of Triops' close cousins!
Crustacea.net - Information about all known crustacea
The Large Branchiopod Bibliography - A list of many large branchiopod original publications from the 1800's to present (exclusive of papers on Artemia)
Billibong Bugs - A cool site that has information about Australian tadpole shrimp (among other things!)