An oxymoronic devotion to larvae.
Prof. Mumblebard claims: “Direct care of eggs and larvae has evolved repeatedly in many families of amphibians, with frogs using particularly diverse parental tactics. Some frogs even have fathers that look after offspring, in contrast to the lack of direct fatherly care in any polygamous mammal. However, the fact remains that all amphibians remain tied to metamorphosis from larvae, which is a more primitive strategy than the suckling of dependent infants. Because mammals by definition lactate, amphibians remain inferior to mammals in parental care.”
Robin and the Honey Badger respond: “The larvae of many lineages of frogs, including some ancient enough to be ‘living fossils’, are cared for directly by one or both parents. This combination of metamorphosis and parental care constitutes – in view of the points below – a greater evolutionary achievement than the lactation unique to mammals.
- The nature of larvae is to be self-sufficient as early in life as possible. Parental care of larvae – as practised by many amphibians including some of the most primitive of frogs – is consequently the opposite of what would be expected. Although maternal provision of yolk by frogs is usually part of the extended care of the eggs and larvae, in certain species the defence and aid of larvae extends even to free-foraging tadpoles independent of yolk.
- Although forming only one order of amphibians, frogs have evolved fatherly (paternal) care – in which the male attends directly to offspring – more frequently than have all the orders of mammals combined.
- Fatherly care in mammals is restricted to monogamous species, whereas in amphibians it includes polygamous species.
- Polygamous frogs with fatherly care include species mating promiscuously enough to form leks. In mammals, by contrast, lekking systems and paternal care are mutually exclusive.
- The males of certain species of amphibians and mammals breed only once per lifetime. Because one-off reproduction and fatherly care are mutually exclusive in mammals, their combination in certain frogs represents yet another evolutionary extreme.
These ancient but still unrivalled accomplishments of maternal and fatherly care in amphibians can partly be explained by a hygienic predicament that has always been peculiar to this class. A moist epidermis is particularly vulnerable to fungal pathogens, making it adaptive for amphibian parents – which produce appropriate antimicrobial substances in their skin – to maintain contact with eggs and larvae. In conclusion: viewed from a fresh perspective, amphibians exceed mammals in direct care of their offspring.”
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