DISSERTATION RESEARCH: Biomechanical and Life Historical Challenges to Performance in Early Juvenile Ascidians

Michael LaBarbara和Kristin Sherrard与陆地动物不同，许多海洋动物从最早的幼体阶段完全独立，长度为十分之一毫米。在这种规模下，摄食、生长和生存面临着独特的挑战。水的行为就像蜂蜜，运输成本很高，被虾踩到是致命的，食物本身，如藻细胞，相对于你的嘴要大得多。人们对海洋无脊椎动物幼体如何面对这些挑战知之甚少，尽管死亡率比随后的任何阶段都要高，这表明早期幼体的表现可能是繁殖成功的关键决定因素。研究人员正在调查早期幼年海鞘的摄食性能、生长速度和死亡率。海鞘的功能很像蛤，过滤水以摄取微小颗粒。它们的生长形式多种多样，可能是群居的，萌发出小的摄食单位，也可能是单生的，体型大大增加。幼体的初始长度变化10倍，有些物种的成体长度可达10厘米，在生长过程中长度变化达1000倍。研究人员将比较相同物种的幼体和成体海鞘以及不同生长模式物种的幼体之间的悬浮喂养性能。他们将确定小尺寸滤料的机械效率是否低于大尺寸滤料，并评估在生命周期的不同阶段性能优化的程度。比较六种远亲海鞘的摄食性能，将揭示是否有多种策略来最大限度地减少小型阶段摄食效率和生长的困难。

Michael LaBarbara and Kristin Sherrard Unlike land animals, many marine animals are fully independent from the earliest juvenile stages, a tenth of a millimeter long. At this size there are unique challenges to feeding, growth, and survival. Water behaves like honey and is costly to move through, being stepped on by a shrimp is fatal, and the food itself, such as algal cells, is much larger in relation to your mouth. Little is known about how marine invertebrate juveniles face these challenges, although mortality rates are higher than at any subsequent stage, which suggests that early juvenile performance may be a crucial determinant of reproductive success. The researchers are investigating feeding performance, growth rates, and mortality in early juvenile ascidian, or sea squirts. Sea squirts function much like clams, filtering water to feed on microscopic particles. They have a variety of growth forms, and may be colonial, budding off small feeding units, or solitary, increasing greatly in size. Initial juvenile length varies tenfold, and some species have adults of up to 10 cm in length, with a thousand-fold length change in the course of growth. The researchers will compare suspension feeding performance between juvenile and adult sea squirts of the same species, and between juveniles of species with different growth patterns. They will determine whether filter feeding at small size is mechanically less efficient than at larger size, and evaluate the extent to which performance is optimized at different stages in the life cycle. Comparing feeding performance in six distantly related species of sea squirts will reveal whether there are multiple strategies to minimize the difficulties of feeding efficiencies and growth at small size stages.