Bio 120 Unit 5 Lecture 6 : Chordates

What is the notochord?

Flexible rod for support and muscle anchoring.

What does the notochord allow?

Swimming movement.

What is the dorsal hollow nerve cord?

Nerve tube along the back.

What does the nerve cord form in vertebrates?

Enlarges at front to become the brain.

What are pharyngeal gill slits for?

Originally filter feeding; later respiration.

What is the post-anal tail used for?

Propulsion in swimming.

What are tunicates also called?

Sea squirts.

Where do tunicates live?

Attached to coral reefs, docks, or surfaces.

Are adult tunicates mobile?

No, adults are sessile; larvae are motile.

How do tunicates feed?

Filter feed with incurrent and excurrent apertures.

What drives water flow in tunicates?

Cilia.

What do tunicates eat?

Bacteria and phytoplankton.

What are larvaceans?

Free-swimming tunicates (e.g., Oikopleura).

What is unique about larvaceans?

Build mucous "houses" to filter food and swim.

What do larvaceans retain for life?

All chordate features.

What are salps?

Jelly-like, transparent, colonial tunicates.

How do salps feed?

Filter feed.

What unique feature do some salps have?

Host commensal fish inside their bodies.

What are lancelets?

Members of Subphylum Cephalochordata (e.g., Amphioxus).

Where do lancelets live?

Buried in sand with heads sticking out.

Do lancelets have all chordate traits as adults?

Yes, all four.

Do lancelets have a brain or backbone?

No, simple nerve cord only.

What are primitive chordates?

Tunicates and lancelets (invertebrates).

What features define vertebrates?

Cranium (braincase), vertebrae (backbone), advanced organs.