Biology Notes 3-19-08

Biology Notes 3-19-08 - Biology Notes Hemichordates(acorn...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Biology Notes March 19, 2008 Hemichordates (acorn worms) -have three part body plan -proboscis -collar -trunk -capture prey with sticky proboscis and pulls it into mouth in collar -The pharynx opens to outside via pharyngeal slits, a site for gas exchange Chordates: All chordates have: -dorsal hollow nerve cord -a tail extending beyond the anus -a notochord -pharyngeal gill slits are present at some stage, but often lost as adult -the notochord is a core of large cells with fluid filled vacuoles making it rigid but flexible -muscular post anal tail used in swimming Urochordate -group is all marine -90% are ascidians Ascidians -Sea squirts or tunicates -adult body is bag-like and enclosed in a tunic secreted by the epidermis -filer feed with pharyngeal basket -larvae reveal the evolutionary relationships -both urochordates and vertebrates have all the chordate traits as larvae -metamorphose into sessile or tail-less adult Cephalochordates -lancelets -very small, less than 5cm -notochord is retained throughout life and is used in burrowing
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 2

Biology Notes 3-19-08 - Biology Notes Hemichordates(acorn...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online