Unit 8
Chapter 29
Echinoderms
and Invertebrate Chordates
What is an Echinoderm?

Radially symmetrical,
with spiny skin

Endoskeletons of
calcium carbonate
and pincerlike
appendages
What is an Echinoderm?



Water Vascular System
For locomotion, food-getting, and gas
exchange
Tube feet =
tiny suction cups
Diversity of Echinoderms

Sea stars

Brittle stars
Diversity of Echinoderms

Sand dollars

Sea urchins
Diversity of Echinoderms

Sea cucumbers

Sea lilies & feather stars
What is a Chordate?

Phylum Chordata includes:
– Urochordates
(Sea Squirts)
– Cephalochordates
(Lancelets)
– Vertebrates
(all vertebrates)
Dolphin embryo
What is a Chordate?

All Chordates have the following characteristics at
some time during their life:

Notochord = rod-like structure (replaced by
backbone in vertebrates)
Dorsal nerve cord = hollow cord (becomes
spinal cord in vertebrates)
Gill slits (pharyngeal pouches) develop into
gills or disappear
Tail (develops or disappears)



Invertebrate Chordates


Tunicates or sea squirts
Have all chordate characteristics as larva,
but not as adults
Invertebrate Chordates


Lancelets
The only chordate to
retain all characteristics
as an adult