The Echinoderm Portal Five groups are counted among Recent
echinoderms, feather stars and sea lilies (Crinoidea), seastars
(Asteroidea), brittle and basket stars (Ophiuroidea), sea
urchins (Echinoidea) and sea cucumbers (Holothuroidea).
Additional about 15 groups have gone extinct during the long
history of evolution. Echinoderm research in Sweden and at the
Swedish Museum of Natural History has a long history. Sven Lovén
studied sea urchins in the 19th century and Hjalmar Théel
described a new genus of sea cucumbers. At the same time, A.W.
Ljungman in Uppsala described over 70 species of brittle stars
and a sea cucumber. This tradition is continued today by Sabine
Stöhr with research on the classification (taxonomy) and
evolutionary history (systematics) of brittle stars.