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

动物的静息代谢率M与体重W之间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，因为质量比代谢率M/W通常随体重增加而降低。这种现象是众所周知的种间（物种之间）以及种内（物种内）。代谢的个体发生（种内M/W随生长的变化）是一个复杂的过程，其中可以区分几个阶段。然而，代谢的个体发生的确切性质和生物学意义尚未在硬骨鱼类中建立，因为幼体和幼体非常小和脆弱。在这里，我们表明，M/W的东方鲀rublipes随着体重的增加而减少，但它突然增加，并伴随着严重的同类相食时，到一定的生长阶段。在呼吸测定中发现，在0.0008-3g湿体重范围内，河豚鱼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0.002，0.01和0.1g附近有三次突然或短期增加，但质量指数保持不变（B=0.82）。有三个相食高峰对应的这些增加的'a_i'。a_i随体重增加或生长而增加是不寻常的，但如果仔细进行呼吸测量，则会在各种硬骨鱼中发现。在比目鱼Paralichthys olivaceus和鲭鱼Scomber中观察到与河豚相似的现象。在自然条件下，这些现象意味着具有更快生长能力的个体可以获得更高的生存率以降低捕食风险。

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.