Invertebrate Chordates Flashcards
What are the three major clades or chordates?
- Lancelets.
- Tunicates.
- Vertebrates.
What is the difference between Tunicates and Lancelets?
Lancelets retain a chordate body plan throughout life while tunicates only have a full chordate body plan in larvae.
What are the five chordate characteristics?
- Dorsal, hollow nerve cord.
- Postanal tail.
- Notochord.
- Pharyngeal slits.
- Endostyle.
What is the notochord?
Axis for muscle attachment and allows body movements.
What are the pharyngeal slits?
Slits that can be used for filter feeding in invertebrate chordates and develop into gill arches in vertebrates. Develops into jaw, tongue, larynx, trachea and ear in terrestrial vertebrates.
What is the endostyle?
Elongated ciliated groove on pharyngeal floor.
What is the dorsal nerve cord dorsal to?
The alimentary canal.
What are the three groups of tunicates?
- Sea squirts. - 90% of all tunicates.
- Thaliaceans.
- Larvaceans.
Give characteristics of Tunicates.
- Adult body baglike and enclosed in a tunic of proteins and complex polysaccharides secreted by epidermis.
Give characteristics of sea squirts.
- Sessile as adult, free-living as larvae.
- Solitary and colonial.
- Form colonies by budding from single founder.
- Pharynx enlarged into pharyngeal basket.
Give characteristics of Larvaceans.
- Tadpole-like.
- Solitary.
- Planktonic.
- Build large casings of sticky mucus to trap organic particles.
Give characteristics of Thaliaceans.
- Live single or in chainlike colonies.
Give characteristics of Lancelets.
- Laterally compressed, fishlike, translucent.
- Oral head with tentacles around mouth.
- Long pharyngeal slits lined with mucus.
What characteristics do hemichordata share with chordata?
Dorsal hollow nerve cord and pharyngeal slits.
What are the two main groups of hemichordates?
Enteropneusts and pterobranchs.
