Chapter 3 Flashcards
20 classes including star fish, sea urchins, sea cucumbers, etc
Echinoderms
Characterized by a calcium carbonate skeleton and secondary radial symmetry
Spiny
Echinoderms
Subphylum also termed enteropneusta (acorn worms)
Hemichordates
Three classes of filter feeders with notochord confined to tail in the free-swimming larval form
Urochordates (tunicata)
Also known as sea squirts or tunicates covered w/ tunic of cellulose like tunicin
Best known class and only one that undergoes complete metamorphosis
Ascidians
Small planktonic individuals
Larvaceans, thaliaceans
Live in gelatinous matrix with screens for water to come in and go out
Larvaceans
Non feeders; trunk with immature viscera and notochord-stiffened tail with uninucleated striated muscle fibers (multinucleate in vertebrates)
Larval sea squirts
Larval sea squirts nervous system
Dorsal hollow nerve cord, several ganglia, plus nerves, and a brain w/ a sensory vehicle that houses an otolith and an ocellus
Otolith
Stratoreception
Ocellus
Light reception
How does water move through a larval sea squirt
Exterior water> mouth> bronchial basket(pharynx)> gills lining the pharyngeal slits> atrium(chamber surrounding pharynx)> exits via atriopore
Has 3 adhesive Padilla to attach larva to substrate to undergo metamorphosis
Larval sea squirt
Notocord and tail is resorbed and both nervous system and viscera are rearranged
Adult sea squirt
How does an adult sea squirt eat
Filter feeding- food particles trapped in mucus from the endostyle and moved by cilia into stomach
How does water move through adult sea squirt
Respiratory water> incurrent siphon> over gills> atrium> excurrent siphon
How does blood flow in adult sea squirt
Blood flows back and forth to distribute gasses and nutrients.
Different from other animals that have 1 way blood flow
What is a cloaca
Sewer (sees urine and fecal material)
What are thaliaceans
Free living, but goes through changes
No gonad, just bud
2 lower subphylum of Phylum chordata with bilateral symmetry, duterosome development, notochord, dorsal hollow CNS, pharyngeal slits, postanal tail, endostyle (no vertebrae)
Protochordates
Urochordata class thaliacea reproduction
Buds- no gonad
Thaliaceans water flow
Bronchial and atrial siphon at opposite ends
Feeding current of water turns into a modest propulsive jet
How do cephalochordates eat
H20 in pharynx> paryngeal slits> atrium> midventral atriopore> exterior
How does respiration occur in amphixous lancelet, cephalochordates
Respiration occurs through the skin
The pharynx does not have a respiratory function
Integument (skin) has a single layer of epithelial cells; thin dermis; connective tissue/muscle
Amphixous
