SYMMETRY, LOCOMOTION, AND THE EVOLUTION OF AN ANTERIOR END - A LESSON FROM SEA-URCHINS
SYMMETRY, LOCOMOTION, AND THE EVOLUTION OF AN ANTERIOR END - A LESSON FROM SEA-URCHINS
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DOI：
10.1111/j.1558-5646.1994.tb05300.x
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发表时间：
1994-08-01
期刊：
影响因子：
3.3
通讯作者：
GRABOWSKY, GL
中科院分区：
文献类型：
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作者：
GRABOWSKY, GL
双侧对称的“规则”海胆在棘皮科（棘皮纲；棘皮门）被发现缺乏前肢运动。在运动中观察到异心哺乳动物和棘球蚴。发现两个椭球体物种的成员以统计上相等的频率首先以其短轴或长轴进行。这一发现表明，两侧对称性的进化并不总是伴随着运动“前”端的进化。椭圆棘海胆为研究体型进化与运动行为之间的关系提供了一个特别合适的研究群体。虽然放射状对称的规则海胆（棘突鱼的起源）缺乏前运动，但所有“不规则”的棘突鱼（也源于规则的祖先，但两侧对称）都具有“专用”前运动。因此，椭圆形棘突海胆所表现出的对称性和行为表明，第一批不规则棘突海胆（根据定义，它们表现出两侧对称）不需要像今天这样拥有前肢运动。
Bilaterally symmetrical, ''regular'' sea urchins in the Family Echinometridae (Class Echinoidea; Phylum Echinodermata) were found to lack a locomotor anterior. Heterocentrotus mammillatus and Echinometra mathaei were observed while locomoting. Members of both ellipsoidal species were found to proceed with their short or long axis foremost with statistically equivalent frequencies. This finding demonstrates that the evolution of bilateral symmetry is not always accompanied by the evolution of a locomotor ''anterior'' end. The elliptical echinometrid sea urchins provide a particularly appropriate study group for investigating the relationship between the evolution of body form and locomotor behavior. Although the radially symmetrical regular sea urchins, from which the echinometrids sprang, lack a locomotor anterior, all ''irregular'' echinoids, which are also derived from a regular ancestor but are bilaterally symmetrical, possess an ''obligate'' locomotor anterior. The symmetry and behavior exhibited by the elliptical echinometrid sea urchins therefore demonstrates that the first irregular echinoids (which exhibit bilateral symmetry by definition) need not have possessed a locomotor anterior as they do today.