Crinoids were very common in warm, shallow seas in the past. Their stems are abundant as fossils around Cincinnati, and entire specimens can sometimes be found in limestones near Brookville Lake. Sea lilies are living crinoids that remain in tropical seas, using their arms to capture plankton for food. Sea stars, while commonly called starfish, are not fish and live in diverse colors and shapes, using tube feet and a water vascular system to feed on bivalve mollusks.

1. Phylum: EchinodermataPhylum: Echinodermata
The Spiny-skinned AnimalsThe Spiny-skinned Animals

2.  Class: Crinoidea:
 Ex. Crinoids

3. Crinoids (Class: Crinoidea) were
very common inhabitants of the
warm, shallow seas that once
covered what is now Ohio. Fossils of their stems are extremely
abundant around Cincinnati. Rarely, a whole crinoid fossil will
be found locally. Entire specimens are in the limestones
around Brookville Lake.
stem
Stem in cross
section
stem

4. This is a Sea Lily.
A living species of
crinoid. Very few
species remain.
Most are brightly
colored and they
live in tropical seas.
This species is from
the Caribbean.

5. Sea lilies stretch out
their arms to capture
passing plankton for
food.

6. Sea Lily –
Tunicate Cove,
Belize

7. Class: Asteroidea
As a child you probably
grew up calling this a
starfish. It isn’t a fish. It
isn’t even closely related to
a fish and it certainly isn’t a
star. It is more appropriately
called a sea star.
Most people picture sea stars as brown or tan animals. This is true
only for those species that live on sand. Species that live on coral
reefs are often cryptically colored to blend with sponges and
polyps.

9. https://www.youtube.com/watch?v=HPhAGyDceLo
Tube feet video

10. Sea stars come in
a diversity of
sizes, shapes, and
colors. This is a
bat star. The
name originates
from the skin
stretched between
the arms like a
bat’s wings.

11. Sea stars come in
a diversity of
sizes, shapes, and
colors. This is a
bat star. The
name originates
from the skin
stretched between
the arms like a
bat’s wings.
Most sea stars are predators that use their
water vascular system and tube feet to pry
open bivalve mollusks.

13. These photographs show the
diverse colors of sea stars as well
as the fact that some species have
more than five arms.

14. These photographs show the
diverse colors of sea stars as well
as the fact that some species have
more than five arms. Those with
more than nine arms are called
Sun Stars.

15. Brittle stars have long,
stringy arms. They
move by walking with
their arms. Their tube
feet are like cleats to
provided added traction.

18. https://www.youtube.com/watch?v=I-F4JQsfOzY
Brittle star locomotion