Revista de Biología Tropical ISSN Impreso: 0034-7744 ISSN electrónico: 2215-2075

Why do velvet worm spermatozoa swim for years?
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female and male gametes
high reproductive investment of onychophorans
environmental pressure
female selection
gametos femeninos y masculinos
alta inversión reproductiva de onicóforos
presión ambiental
selección femenina

How to Cite

Monge, J. (2019). Why do velvet worm spermatozoa swim for years?. Revista De Biología Tropical, (1), Darwin. Retrieved from


The sperm of many onychophorans must cross body walls and swim for years before fertilizing an egg. We propose that the cause for such obstacles is the high cost of reproduction in these animals, which leads females to select eggs early in their development; and to invest heavily in their atypically large Golgi apparatus and in the production of glycogen. Velvet worm spermatozoa are subjected to a marathon that selects the most resistant.

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