Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, Dalian, 116023, China.
Sci Rep. 2021 May 11;11(1):9985. doi: 10.1038/s41598-021-89471-2.
Interaction among sea urchins remains largely uninvestigated, although the aggregation of sea urchins is common. In the present study, 1, 15 and 30 sea urchins Strongylocentrotus intermedius (11.06 ± 0.99 mm in test diameter) were placed in a 1 m circular tank, respectively. Movement behaviors were recorded for 12 min to investigate potential interactions among sea urchins. After the 12-min control period, we added food cues into the tank and recorded the changes in sea urchins' behaviors. For the first time, we here quantified the interactions among sea urchins in laboratory and found that the interactions varied with food cues and with different densities. The sea urchins dispersed in random directions after being released. There was no significant difference in the movement speed and the displacement of sea urchins among the three density groups (1, 15 and 30 ind/m). The interaction occurred when sea urchins randomly contacted with the conspecifics and slowed down the movement speed. The speed of sea urchins after physical contacts decreased by an average of 40% in the density of 15 ind/m and 17% in the density of 30 ind/m. This interaction resulted in significantly higher randomness in the movement direction and lower movement linearity in 15 and 30 ind/m than in 1 ind/m. After the introduction of food cues, the movement speed, displacement and dispersal distance of sea urchin groups decreased significantly in all the three densities. The dispersal distance and expansion speed of sea urchins were significantly lower in 30 ind/m than those in 15 ind/m. The present study indicates that the interaction among sea urchins limits the movement of individual sea urchin and provides valuable information into how large groups of sea urchins are stable in places where food is plentiful.
棘皮动物之间的相互作用在很大程度上尚未被研究，尽管棘皮动物的聚集是很常见的。在本研究中，分别将 1、15 和 30 只直径为 11.06±0.99 毫米的中间棘皮海胆放入 1 米的圆形水箱中。记录了 12 分钟的运动行为，以研究棘皮动物之间的潜在相互作用。在 12 分钟的对照期后，我们向水箱中添加了食物线索，并记录了棘皮动物行为的变化。我们首次在实验室中量化了棘皮动物之间的相互作用，并发现这种相互作用随食物线索和不同密度而变化。棘皮动物在释放后向随机方向扩散。在三个密度组（1、15 和 30 个/平方米）中，棘皮动物的运动速度和位移没有显著差异。当棘皮动物随机接触同种个体时，就会发生相互作用，并减缓运动速度。在密度为 15 个/平方米和 30 个/平方米时，棘皮动物在物理接触后的速度平均下降了 40%和 17%。这种相互作用导致在 15 和 30 个/平方米的密度下，运动方向的随机性显著增加，运动直线性显著降低。在引入食物线索后，所有三个密度组的棘皮动物运动速度、位移和扩散距离都显著降低。在 30 个/平方米的密度下，棘皮动物的扩散距离和扩展速度明显低于 15 个/平方米的密度。本研究表明，棘皮动物之间的相互作用限制了个体棘皮动物的运动，并为大量棘皮动物在食物丰富的地方保持稳定提供了有价值的信息。
