Pondcast 17: April 25-May 1, 2010

Aquatic life abounds in Black Pond in Week 17. But gone from the waters are mosquito pupae. They have metamorphosed into adults and have left the water. The caddisfly larvae are still developing. This week when they emerge from their pupal cases, we can see the silk on their bodies that is used to make this shelter. A few fairy shrimp were seen swimming about as well as predaceous diving beetle larvae.

On the surface of the pond, water striders can be seen skating about here and there in search of prey. Water striders are true bugs of the Insect Order, Hemiptera, Family Gerridae. Lacking fully developed wings, the legs of these predators allow them to remain on the surface of still water found in ponds, swamps, and slow-moving streams. Their legs allow water striders to detect vibrations of their prey who also live on the water’s surface. Like other true bugs in the Insect Order, Hemiptera, water striders possess mouth parts for sucking the juice out of their prey.

New this week were red and black water mites. Several of these 2mm spheres with legs were observed. Water mites are arachnids and have a taxonomic classification more confusing than their complex life cycle. Water mite eggs hatch into free-swimming larvae. The larvae then attach themselves to a host insect and become parasites, feeding off their host’s tissues. The larva enters a nymph stage, which like an adult water mite, is a free-swimming predator of small crustaceans, like water fleas (daphnia).

Several insects each called, water boatmen, made an appearance this week. Like water striders, these are true bugs of the Insect Order, Hemiptera of the Family Corixidae. Of all the aquatic bugs, this is the largest family, with over 100 species and they all look pretty much alike. Water boatmen are herbivores, eating only algae.

We have seen the crustaceans known as ostracods early on in our pond study, in the form of seed shrimp. However, in spring another ostracod appears in Black Pond. This ostracod is orange in color, about 3-5mm in size and is round in shape. Two, hinged shells, reminiscent of a free-swimming oyster or scallop, surround its legs.

Stefan Szumko is a middle school science teacher by trade, an outdoor environmental educator by calling, and a homedaddy by choice. He can be reached at slugwhisperer@gmail.com. To view all the video pondcasts, visit his YouTube channel at http://www.youtube.com/user/slugwhisperer.