Phylum Nemertea

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Phylum Nemertea
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What do Nemerteans look like?
Ribbon worms Most benthic marine Complete
digestive system Eversible proboscis Circulatory
system
Fig. 1
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How do Nemerteans support themselves and move?
Hydrostatic mesenchyme and muscular antagonistic
system. Small nemerteans use cilia. Large move
with peristaltic waves.
Fig. 2
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How do Nemerteans support themselves and move?
Cephalization with ladder-like nervous
system. Sense organs.
Fig. 10
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How do Nemerteans feed themselves?
Eversible proboscis which is a blind tube in a
rhyncocoel. Proboscis often has toxins on
stylets. After prey subdued, it is drawn into
mouth.
Fig. 6
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How do Nemerteans feed themselves?
Complete gut.
Fig. 7
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How do Nemerteans circulate oxygen and nutrients?
Closed circulatory system longitudinal and
lateral vessels with cephalic and anal
lacunae. Gas exchange across epidermis.
Fig. 8
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How do Nemerteans osmoregulate and remove wastes?
Protonephria with flame bulbs associated with
blood vessels.
Fig. 9
Fig. 8
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How do Nemerteans reproduce and develop?
Asexual reproduction
Regeneration. Multiple transverse fission.
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How do Nemerteans reproduce and develop?
Sexual reproduction
Most gonochoristic. Gonads are in tissue along
gut.
Fig. 12