Respiration
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Pattern of circulation over (broken arrows) and within (solid arrows) a sea anemone, including flows in the pharynx. Arrows on the right and left illustrate a flow pattern on a mesentery and between mesenteries respectively. Adapted from Ruppert, Fox & Barnes (2004). |
Sea anemones do not have oxygen-carrying respiratory pigments and rely on diffusion1,2. Water is circulated over the body surface and the gastrodermis by ciliated epidermal cells to facilitate gas exchange between the tentacles and the general body wall2. Although individuals may reach rather large sizes, having a primarily two-dimensional and laminar body plan minimizes diffusion distance and hence enhances oxygen delivery. As a result, oxygen consumption is almost directly proportional to body mass1.
1Shick 1991
2Ruppert, Fox & Barnes 2004 |