Unit 8Chapter 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