Linkage between metabolic ontogeny and cannibalism in perch-like fish and their derivatives

动物静息代谢率M与体质量W的关系用异速生长公式M=aW^b表示，其中a为质量系数，b为质量指数。质量指数小于1，因为质量特定代谢率M/W通常随着体重的增加而降低。这种现象在种间（种之间）和种内（种内）都是众所周知的。代谢的个体发生（种内分子量随生长变化）是一个复杂的过程，可分为几个阶段。然而，由于硬骨鱼的幼体和幼体非常小和脆弱，其代谢个体发生的确切性质和生物学意义尚未确定。研究表明，河豚的肉重比随着体重的增加而降低，但到了一定生长阶段，肉重比会突然增加，并伴有严重的同类相食。我们在呼吸测量中发现，在湿体质量0.0008-3g范围内的羽化体有四个独立的异速生长公式M/W=a_iW^<b-1>，其中质量系数a_i在保持恒定的质量指数（b=0.82）的情况下，在0.002、0.01和0.1g左右突然或短时间内增加了三倍。与“a_i”的增加相对应的是三个同类相食的高峰。‘ a_i’随体重增加或随生长而增加是不寻常的，但如果进行仔细的呼吸测量，可以在各种硬骨鱼中发现它。与河豚鱼相似的现象在鲽鱼（paricichthys olivaceus）和鲭鱼（Scomber japonicus）中也观察到。在自然条件下，这些现象意味着生长能力越快的个体存活率越高，从而降低了捕食风险。

The relationship between resting metabolic rate M and body mass W of animals is expressed by an allometric formula M=aW^b, where ‘a' is mass coefficient and ‘b' mass exponent. Mass exponent is smaller than unity, because mass-specific metabolic rate M/W usually decreases with increasing body mass. This phenomenon is well known interspecifically (among species) as well as intraspecifically (within a species). The ontogeny of metabolism (intraspecific change of M/W with growth) is a complex process in which several phases can be distinguished. However, the precise nature and the biological meaning of the ontogeny of metabolism have not been established in teleost fishes, because of very small and fragile nature of larvae and juveniles. Here we show that M/W of a puffer fish Takifugu rublipes decreases with increasing body mass, but it increases abruptly accompanying a severe cannibalism when getting to a certain growth stage. We found in respirometry that the puffer ranging 0.0008-3g in wet body mass had four independent allometric formulae M/W=a_iW^<b-1>, in which the mass coefficient ‘a_i' increased three times abruptly or in a short period at around 0.002, 0.01 and 0.1g, although keeping a constant mass exponent (b=0.82). There were three peaks of cannibalism corresponding to these increases of ‘a_i'. Increases of ‘a_i' with increasing body mass or with growth are unusual, but it would be found in various teleost fishes, if careful respirometry were taken. Similar phenomena to the puffer fish were observed in a flounder Paralichthys olivaceus and a mackerel Scomber japonicus. In the natural condition, these phenomena imply that individuals with growing ability more rapidly are assured of higher survival to reduce predatory risk.