NEMERTEA Flashcards
General Characteristics of Nemertea
Bilateral symmetry
Triploblastic
Unsegmented
Complete digestive tract
Closed circulatory system
Unique proboscis structure
Mostly benthic marine
2 classes (and 1 subclass)
Class Paleonemertea
Class Neonemertea
—Subclass Hoplonemertea
What is special about Class Paleonemertea?
Proboscis is not armed with stylets
Mouth separate from proboscis opening
What is special about Class Neonemertea?
Proboscis that is armed with stylets associated with toxins
Mouth and proboscis share an opening
How do Nemerteans support themselves?
Hydrostatic mesenchyme and muscular antagonistic system (muscle layers in different orientations).
What is special about their epidermis?
It is ciliated
How do they move?
Crawl w/ muscle contractions (peristaltic waves)
Small species can move with cilia and mucus
How do they sense their environment?
Cephalization with ladder-like nervous system.
Sense organs – very sensitive to chemicals.
Complete or incomplete gut?
Complete
Open or closed circulatory system?
Closed
Gas exchange across _____?
epidermis
Osmoregulation/ waste removal done with ______?
Protonephridia with flame bulbs associated with blood vessels.
Asexual reproduction?
Regeneration
Multiple transverse fission
Sexual reproduction?
Most gonochoristic
Gonads are in tissue along gut
What type of cleavage?
Spiral
