Telford Malcolm, Mooi Rich, Ellers Olaf
Biol Bull. 1985 Oct;169(2):431-448. doi: 10.2307/1541493.
The feeding mechanism of Mellita quinquiesperforata (Leske) has been examined in detail. This sand dollar is a deposit feeder, ingesting particles mostly in the range of 100-250 µm. The particles are picked out of the substrate individually by specialized long barrel-tipped podia, which form a narrow palisade surrounding the geniculate spine fields on the oral surface. Selected food items are passed to short barrel-tipped podia, thence from podium to podium until they reach the food grooves where they are finally aggregated into mucus cords. The cords are passed to the mouth by the activity of food groove podia. At the peristome, the cord is passed between the circumoral spines by large food groove podia and steered into the mouth by five pairs of buccal podia. The lantern is powerfully muscled and has hardened teeth which crush diatoms and fracture many sand grains. For this reason, there is an apparent accumulation of fine particles (<50 µm) in the gut. Analysis of size frequencies of the material in the mucus cords and substrate indicates that no selection of fine particles occurs and, in fact, that they are virtually absent from the native sediment. An account of spine and podial morphology and distribution is included with descriptions and measurements of surface ciliary currents. It is shown that the formerly accepted sieve hypothesis of feeding cannot be entirely rejected on theoretical grounds. However, during feeding there was no evidence of the operation of any of the elements of the supposed sieve mechanism. Furthermore, the ciliary currents are not fast enough to account for the movement of most ingested material. Patterns of ciliary flow on the oral surface are not simply centripetal, but are much more complex than previously supposed.
已对五孔砂海星（莱斯克）的摄食机制进行了详细研究。这种海胆是沉积取食者，摄取的颗粒大多在100 - 250微米范围内。颗粒由专门的长筒状末端的管足从基质中逐个挑选出来，这些管足在口面围绕膝状棘区域形成一个狭窄的栅栏。挑选出的食物被传递到短筒状末端的管足，然后从一个管足传递到另一个管足，直到它们到达食物沟，在那里最终聚集形成黏液索。黏液索通过食物沟管足的活动被传递到口中。在口周围，黏液索由大型食物沟管足在围口棘之间传递，并由五对颊管足引导进入口中。口器肌肉发达，有坚硬的牙齿，可碾碎硅藻并破碎许多沙粒。因此，肠道中明显积累了细颗粒（<50微米）。对黏液索和基质中物质的尺寸频率分析表明，没有对细颗粒进行选择，实际上，在原生沉积物中它们几乎不存在。文中还包括了棘和管足的形态及分布描述，以及表面纤毛流的描述和测量。结果表明，以前被接受的摄食筛滤假说在理论上不能完全被否定。然而，在摄食过程中，没有证据表明假定的筛滤机制的任何要素在起作用。此外，纤毛流的速度不足以解释大多数摄入物质的移动。口面的纤毛流动模式并非简单的向心式，而是比以前认为的要复杂得多。
