Convolutidae - Characteristics

Characteristics

Acoels with a ventral mouth opening. Body-wall musculature with circular, longitudinal, and longitudinal crossover muscle fibers in both the dorsal and ventral body wall, and U-shaped fibers in the ventral body wall.

Male copulatory organ with muscular, often glandular, tubular penis. Penis musculature with inner circular fibers and outer longitudinal fibers that anastomose or cross over each other. When present, a muscular seminal vesicle surrounds all of, or a portion of the penis. Male gonopore ventral, subterminal, or terminal at posterior end; usually positioned behind opening to female seminal bursa. Spermatozoa with 9+0 axonemes and axial microtubules.

Algal symbionts often present. Ocelli, when present, contain reflective platelets in the pigment cell and lack cilia or microvilli as receptor organelles (Hooge & Tyler, 2005).

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