Ephemerellidae are known as the Spiny Crawler Mayflies. They are a family of the order Ephemeroptera. There are 8 genera consisting of a total 90 species (Merritt & Cummins). They are distributed throughout North America as well as the UK. Their habitat is lotic-erosional, they are found in all sizes of flowing streams on different types of substrates where there is reduced flow. They are even found on the shores of lakes where there wave action present. They move by swimming and clinging, they are very well camouflaged. Most species have one generation per year. They are mostly collector-gatherers.

If threatened by a predator, the larva will raise its three tails in a "scorpion posture" to appear larger. It will then project its tails in front and poke the enemy. Most species are sensitive to disturbance.

In the UK, the most commonly recorded species is Seratella ignita. The nymph of this animal is often distinguished from other Mayflies by the darker bands prominent on the legs and tails. Although another rare species Ephemerella notata lacks these prominent bands, and so are more difficult to identify.