Which statement describes a typical feature of Nematoda?

Prepare for the IB Marine Science SL Exam. Use flashcards and multiple-choice questions with detailed explanations. Master marine ecosystems, ocean currents, and biological resources for success!

Multiple Choice

Which statement describes a typical feature of Nematoda?

Explanation:
Nematodes are characterized by a pseudocoelomate body plan, meaning they have a fluid-filled cavity between the endoderm and mesoderm rather than a true coelom lined by mesoderm. This pseudocoel acts as a hydrostatic skeleton that helps their long, slender bodies move with only longitudinal muscles. The outer covering is a tough cuticle that is periodically shed as they grow, a process called molting. They lack a true coelom and a circulatory system; nutrients and gases diffuse directly through the body tissues instead. Their body is unsegmented, unlike annelids, and their nervous system is a nerve ring with longitudinal cords, not a dorsal nerve cord inside a bony skeleton. This combination of a pseudocoelom, a moulting cuticle, and the lack of true segmentation or circulatory system best describes a typical feature of nematodes.

Nematodes are characterized by a pseudocoelomate body plan, meaning they have a fluid-filled cavity between the endoderm and mesoderm rather than a true coelom lined by mesoderm. This pseudocoel acts as a hydrostatic skeleton that helps their long, slender bodies move with only longitudinal muscles. The outer covering is a tough cuticle that is periodically shed as they grow, a process called molting. They lack a true coelom and a circulatory system; nutrients and gases diffuse directly through the body tissues instead. Their body is unsegmented, unlike annelids, and their nervous system is a nerve ring with longitudinal cords, not a dorsal nerve cord inside a bony skeleton. This combination of a pseudocoelom, a moulting cuticle, and the lack of true segmentation or circulatory system best describes a typical feature of nematodes.

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