التعريف: overall repetitive or reflective pattern in the body of one individual of this taxon. eg: bilateral symmetry, rotational symmetry, radial symmetry
التعريف: Living in the fluid medium (water or air) but unable to maintain their position or distribution independently of the movement of the water/air mass (adapted from Lincoln et al., 1998).
التعريف: Expressions of the estuarine biome occur at wide lower courses of a rivers where they flow into a sea. Estuaries experience tidal flows and their water is a changing mixture of fresh and salt.
التعريف: Drag swimmers use a cyclic motion where they push water back in a power stroke, and return their limb forward in the return or recovery stroke. When they push water directly backwards, this moves their body forward, but as they return their limbs to the starting position, they push water forward, which will thus pull them back to some degree, and so opposes the direction that the body is heading. This opposing force is called drag. The return-stroke drag causes drag swimmers to employ different strategies than lift swimmers. Reducing drag on the return stroke is essential for optimizing efficiency.
التعريف: An interaction relationship involving a predation process, where the subject kills the target in order to eat it or to feed to siblings, offspring or group members
التعريف: A group of species that exploit the same food resources, and/or use the same feeding or foraging methods. http://en.wikipedia.org/wiki/Guild_(ecology)
التعريف: Relative to pinhole eyes, lens eyes have greatly improved resolution and image brightness. The lens converges incoming rays of light, thereby reducing the angle over which each photoreceptor receives light, and forming an image focused on the retina. Most lens eyes have "accommodation"; they can focus an image either by physically moving the lens toward or away from the retina or by using eye muscles to adjust the shape of the lens.
