Night crawlers   Lee E. Frelich
  Jan 26, 2007 06:08 PST 

Paul et al.:

Since Woodcocks eat nightcrawlers (Lumbricus terrestris), people often ask
me what they ate before nightcrawlers were introduced to this
continent. The answer is Lumbriculus variegatus (note that the genus is
spelled slightly different), which is an aquatic worm native to most of
North America and common in riparian areas.

Lumbriculus accumulates toxic metal pollution that is present in many
aquatic sediments these days, which is why there are so many studies of
metals in woodcocks, which still eat Lumbriculus in addition to Lumbricus.

Lumbricus terrestris is probably the best suited of the exotic earthworms
to invade riparian areas where Lumbiuculus lives, as long as they are
alkaline, because it uses Ca to scrub CO2 from their blood under
microaerophilic conditions (<5% oxygen). Nightcrawlers eat leaves with high
Ca content (ash, basswood, maple), and extract the Ca, and combine the Ca
with CO2 to form Calcium Carbonate, which they excrete. Nightcrawlers can
survive in microaerophilic conditions such as an aquarium with an
oxygenator, for at least two weeks (one of my graduate students did the
experiment). A nightcrawlers is bigger than a Lumbriculus, so its a real
treat for a woodcock--a lot to eat for relatively little work.


PS--there will be an earthworm physiology quiz at the next ENTS meeting