Phylum Nemertea (Ribbon worms)

Superphylum?

Lophotrochozoa

Body Plan?

Bilateral

Tissues?

Triploblastic

Body cavity?

Acoelomate

Considered to be a protostome?

Yes

Defining characteristic

Eversible proboscis

Located in the rhynchocoel

Harpoons prey

Some have barbs

Almost all are ____ marine

benthic

Size varies widely

1 cm- several meters in others

Simple cephilization

Cerebral ganglia comprise a rudimentary “brain”

Sensory papillae provide sense of touch (located near mouth)

Ocelli are present in most species

Most are?

Carnivorous

Digestive system?

Complete

Has mouth and anus, food travels in one direction

Prey enters mouth, foregut, then intestines

Exits through anus

Circulatory system?

Has

Closed circulatory system

Loop formed by a pair of connected blood vessels

Blood flow is maintained by muscle contraction

Excretory system

Has

Pair of tubule called protonephridia (early kidney)

Removes metabolic waste and maintains osmoregulation

Nervous System?

Has

Rudimentary brain of four ganglia around the head and rhynchocoel

Pair of lateral nerves emerge on either side of the brain and travel length of the body

Most have ocelli, in pairs

Respiratory system?

Lacks

Limits thickness of body

O2 and CO2 through epidermis

Reproduction

Highly regenerative

Asexual via fragmentation

Mostly dioecious

Gonads

Along digestive tract

Stem cells

Courtship spawning

External fertilization

Larvae

Develop into trochophore larvae, growth through several larval stages