Aquatic invertebrates of the Rideau River: Meet the order of amphipods.
Class: Crustacea - Crustaceans
Order: Amphipoda - Amphipods
Family: Hyalellidae - Hyalellids
Species found in the Rideau River:
Characteristics of the family:
Members of the Hyalellidae family are small amphipods with relatively
short antennas and large eyes. The last segment of the abdomen is entire,
which means it is not split or cleft. Most live in marine environments
but some of the members live only in freshwater.
||Small bodied, commonly
with 2 to 3 teeth (like on a saw rather than in a mouth) on
the back at the hind end of the body. Colour is variable with
white, green and brown being common, but they can be reddish,
bluish or purple. The 2nd leg of the male is much
larger and broader than that of the female.
||3 to 8 mm (Males
are larger than females).
||Found in permanent
freshwaters of North and Central America, north to the treeline.
Common in the Rideau River.
in lakes or rivers.
algae and diatoms, but may eat decaying organic material as
||For up to a week
before mating, males carry females by grasping the 2nd segment
of the female's body. This is known as precopula. In this way,
males assure themselves a female to mate with when she moults
and the eggs are laid. The female has large plates on the underneath
of her body in which she keeps the eggs. When the young hatch
they look like tiny adults. Breeding takes place when water
temperatures reach 10°C (about April to October near the
Rideau River), with many broods per year.
are quite common along the shoreline, but because of their small
size they are not usually noticed. They are good swimmers and
dart about in the algae.