This is the only spider that lives in the water.
But it still needs to breath air. First, it spins
a dome-shaped web between underwater plants.
Then it collects airbubbels in a diving bell.
After a few trips to the surface the spider
has collect enough air to live in its bell.
That bell is anchored to waterplants, about one
decimeter under the surface of a pond. That diving
bell is a juwel to look at, and its needs a lot of
a hard work to fill it with air.
The spider collects airbubbels on the surface
and uses lines to make a fast descend to
its diving bell.
living in a diving bell
Most of the time it spends it time waiting in the bubble.
During daytime the waterspider only leaves the
diving bell if a prey comes closely.
But at night it swims around in the aquarium hunting
for small fish. The diving bell is also a nursery
for the eggs. Waterfleas or Daphnia are food
for young waterspiders, small fish and waterinsects are
hunted by larger spiders. They use a pepper-like toxine
as a venom. The bite of a waterspider in a finger is painfull.
adaptation of the waterspider
The waterspider made a lot of big adaptations to live
in the water: the use of a diving bell to allow it
to live deeper underwater than normally possible,
but also its adaptation to much lower oxygen levels
than its terrestrial brethren, while at the same
time moving/swimming through a much denser medium.
new research of the waterspider
Physiologist Roger Seymour and Stefan Hetz ( Humboldt
University in Germany) did research on the waterspider
and its bell. They did some discoveries by using a very
small device (optode) that measures oxygen and nitrogen
levels inside the diving bell.
Oxygen that the spider removes from the bell by breathing
in, is partly suppleted by diffusion from the water that
surrounds it. This gives the spider a constant low oxygen
supply without requiring it to venture to the surface often.
It only needs to add some airbubbles after one day.
The key to a gill is keeping its volume proportional to
an animal's body size and oxygen usage. So when the spider
oxygen use is increased by eating its prey, the
waterspider will increase the airvolume of the bell.
Females also enlarge their bells when they're about to
lay their eggs.
waterspiders in the aquarium
The water spider is a living juwel in youre native aquarium
but its also a succesfull predator: sometimes a small fish or newt
disappears.
A girl looks at the aquarium, around 1900.
At that time, an aquarium had no electrical cleaning
pomps, lamps and sieves, no temperature control,
and the water is cleaned by the roots of the fern.
These natural aquaria were common around the fin
du siecle, and were inhibited by the diving beetle,
salamanders, frogfish, stickelbacks and the waterspider.
The waterspider is an easy housepet, and can be
feed with a lot of freshwater animals, like
the larvae of waterinsects, frogfish, small fish etc.
Pondlife in a healthy pond.
1 Edible frog (Rana esculenta)
2 Brown frag (Rana temporalis)
3 Frogfish
4 great diving beetle (Dytiscus marginalis)
5 Waterspider (Argyroneta aquatica)
6 common newt (Triturus vulgaris)
7 European grass snake (Natix natrix)
8 larval stage of Caddisflies or sedge-flies (Trichoptera)
1 Eurasian water milfoil (Myriophyllum spicatum)
2 spatterdock or yellow water-lily (Nuphar luteum)
3Common Water Crowfoot (Batrachium aquatilis)
4 Water-starwort or water-chickweed. (Callitriche verna)
illustrations of A.E. Brehm
Alfred Brehm (1829-1884) is of the writer
"Tierleben " or Brehms "Life of animals".
The illustrations from this book can be found here:
An engraving from Lampert ("das leben der Binnengewasser")
1 Graet raft spider (dolomedes plantarius)
2 Common stretch-spider strekspin (tetragnatha extensa)
3 water spider with air bubble
4 diving bell
5 Triops
6 common freshwater shrimp (gammarus pulex)
7 fresh water fairy shrimp (Branchipus)
8 Red watermite
9 aquatic sowbug
10 Reed sac-spider (clubiona phragmitis)
waterspider, hunting , attacking a pondsnail, in a diving bell,
An engraving of Brehm.
Pondlife in a healthy pond.
The waterspider, an illustration made in 1920.
An engraving from Lampert ("das leben der Binnengewasser")
