Hemichordates and chordates Flashcards
What is the defining feature of chordates?
The notochord
What are the characteristics of phylum hemichordata?
Body divided into proboscis, colalr and trunk
Three cavities in coelom
Ciliated pharyngeal slits
open circulatory system
complete digestive tract
dorsal/tubular nerve cord
What are the two classes of hemichordata?
Enteropneusta & pterobranchia
Summarize class enteropneusta
Acorn worms
Mucous covered body
proboscis is the active part of the animal
collar contains mouth
trunk has rows of gill pores
How do acorn worms feed?
Deposit or suspension feeders
Deposit feeding use the mucous on the proboscis to probe surroundings and collect food and transport it to mouth
How do acorn worms breathe?
Rows of gill pores open from ciliated gill chambers and connect to u-shaped gill slits in pharynx
Summarize class pterobranchia
Similar to acorn worms but more sedentary
Colonial and live in tubes
What purpose does the pterobranch proboscis serve?
Aids in tube secretion
What purpose does the proboscis serve in acorn worms?
‘probes’ surroundings and collects food using mucous strands
What are the 5 characteristics of chordates
Notochord
Dorsal tubular nerve cord
pharyngeal slits
endostyle/thyroid gland
postanal tail
What is the notochord?
Flexible rod that provide support, made of connective tissues
What is the dorsal tubular nerve cord?
Hollow tubular nerve cord
longitudal to body, dorsal to nerve cord
forms central nervous system and was important for complex development
What are pharyngeal slits? Pouches?
Slits - primarily used in filter feeding or respiration
Pouches- internal embryonic structures that become slits in aquatic chordates
What is the endostyle/thyroid gland?
Secretes muscous/hormones
What is a post-anal tail
Tail that goes beyond the anus
