Direct development in a Nudibranch, Cadlina laevis, with a discussion of developmental processes in Opisthobranchia
Direct development in a Nudibranch, Cadlina laevis, with a discussion of developmental processes in Opisthobranchia
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裸鳃亚纲（Cadlina laevis）的直接发育，并讨论后鳃亚纲的发育过程
DOI：
10.1017/s0025315400033518
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发表时间：
1967
影响因子：
1.2
通讯作者：
T. E. Thompson
中科院分区：
文献类型：
--
作者：
Cadlina Laevis;T. E. Thompson
光叶红萤叶甲Cadlina laevis（L.）是英国第一个被证明拥有直接发育能力的裸鳃类物种。胚胎在产卵后约50天（10° C）离开卵囊，身体的一般形式与成虫相似。仍有足够的食物储备，可维持一周以上的底栖生物生命和明显的生长。一个退化的面盘阶段在卵囊内通过。壳，软膜，地幔，和后生基的雏形类似于transitorily后鳃面盘幼虫的器官，但某些面盘结构（幼虫肾脏，软膜运动和足纤毛）是残留在Cadlina，和其他完全缺席（鳃盖，幼虫牵开肌，软膜下脊，后生粘液腺，足感觉纤毛，肾囊肿）。在后鳃类中，可以识别出三种不同的发育类型。1型包括那些具有嗜食性面盘幼虫的物种。第2类包括具有卵营养型幼虫的物种（在Ockelmann，1965年使用的意义上）。第三型的种直接发育，其中许多面盘结构可能在孵化前被简单地概括。类型3的物种拥有最大尺寸的卵，类型2的物种通常拥有较小的卵，而类型1的物种拥有最小的卵。卵的大小与胚胎期的长短呈正相关，与批量大小呈负相关。在任何发育类型中，最大的物种往往产生更大数量的卵。在任何物种中，最大的个体往往比较小的个体产生更多的卵;卵的大小在地理范围内变化不大。
Cadlina laevis (L.) is the first British species of nudibranch shown to possess direct development. The embryo leaves the egg-capsule approximately 50 days (at 10° C) after oviposition, and resembles the adult in the general form of the body. Sufficient food reserves remain to sustain life and apparent growth for more than 1 week of benthic life. A vestigial veliger phase is passed through within the egg-capsule. The shell, velum, mantle, and metapodium-rudiment resemble transitorily those organs of opisthobranch veliger larvae, but certain veliger structures (larval kidney, velar locomotor and pedal cilia) are vestigial in Cadlina, and others are altogether absent (operculum, larval retractor muscle, subvelar ridges, metapodial mucus-gland, pedal sensory cilia, and nephrocysts). In the Opisthobranchia three distinct development types can be recognized. Type 1 includes those species which possess planktotrophic veliger larvae. Type 2 comprises the species which have lecithotrophic larvae (in the sense employed by Ockelmann, 1965). Type 3 species have direct development, in which many veliger structures may be briefly recapitulated before hatching. Species of type 3 possess eggs of the largest sizes, species of type 2 in general have smaller eggs, while species of type 1 possess the smallest eggs. There is a positive correlation between egg size and the length of the embryonic period, and an inverse correlation between both and batch size. Within any development-type, the largest species tend to produce larger eggs in greater numbers. Within any species, the largest individuals tend to produce more eggs than do the smaller individuals; egg size varies little through the geographical range.