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Nausithoe werneri Jarms, 1990 |
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Figure 1
Figure 2
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Nausithoe werneri Jarms, 1990
Almost everybody has seen large medusae on the sea shore, or has even
had an unpleasant encounter with stinging jellyfish while swimming.
There are, however, many more species that can be very small, like this
tiny species from the Anaximander Seamount in the deep eastern
Mediterranean Sea. It is called Nausithoe werneri,
and it was first found by Hjalmar Thiel in the northern Atlantic in
1982 and described by Gerhard Jarms (University of Hamburg) in 1990. He
even succeeded in keeping these fragile creatures alive in his
laboratory to investigate their biology!
The sessile generation, the polyp (Figure 1), has been found in depths
from 200 to 3000 m, often on a very special substrate, pieces of coal
slag coming from steamships of the previous century. It is about 1 cm
long, and it reproduces asexually by separating tiny slices off its
front end (see the feature looking like a stack of plates in Figure 2).
These slices in turn develop into the free living generation, the
medusa, which is what most people know as jellyfish turning up on
beaches now and then. In this species, however, the medusa is just as
tiny as its polyp, only about 1.5 cm in diameter. Like all medusae it
reproduces sexually (the gonads can be seen as eight shiny regions on
the medusa in Figure 3).
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Figure 3
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Figure 1. Polyp of Nausithoe werneri from the Mediterranean, about 900 m depth. Length 1 cm.
Figure 2. Nausithoe werneri, polyp forming medusae (strobilation)
Figure 3. Nausithoe werneri, sexually mature medusa, diameter 1.5 cm.
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