Not an everyday occurrence : A special birth
To report on a birth, especially if it involves the child of a celebrity, is many a journalist’s dream assignment, because it is usually a happy event and a large readership is guaranteed. To some extent this holds true even in cases where not the birth of a human baby is celebrated but that of a rare or endangered animal is reported.
I once witnessed the live birth of an earth-coloured, caterpillar-like creature termed Peripatoides novaezealandiae with very short and stubby unsegmented legs. This matchstick sized, multilegged animal is to the invertebrate zoologist what the egg-laying mammal (the Australian platypus) is to the vertebrate zoologist: a missing link connecting an archaic group with a more advanced branch of organisms. Like worms, peripatuses possess segmentally arranged excretory organs and lack segmented legs, jointed antennae (i.e., feelers), compound eyes and a hard outer cuticle. However, unlike worms and more in line with insects they have biting mouthparts, a tracheal system, a tubular heart and an open circulatory system. The stubby little legs, moreover, end in claws not unlike those of insects, which is the reason why these vermiform invertebrates are also called Onychophora (claw carriers).
Discovered more than a hundred years ago from a Trinidad museum specimen that was initially wrongly classified as a slug, there are now at least 100 species of peripatuses known worldwide, most of them with a tropical and southern hemisphere distribution. In New Zealand, which is of course southern hemisphere, but not tropical, the viviparous species that I had observed giving birth, occurs in native forest stands of the North Island. Combining features of worms and insects, this nocturnal 5 cm long micro-predator leaves its shelter under stones or pieces of rotting logs at night when humidity is high and it can hunt down its prey of small ground spiders or other arthropods with a unique weapon: it spits or better squirts a sticky mucus from around its mouth at its prey and pins it down in this way. The immobilized prey will then allow the rather slow peripatus to leisurely feed on it.
The two genders differ slightly from each other. Females are a little bigger than males and allow the latter to deposit sperm-charged spermatophores on their bodies. Spermatozoans become active and free themselves from the spermatophore presumably through chemicals released from the female’s skin. They then penetrate the female’s wrinkled, but thin body cover and by hitherto insufficiently understood means find the eggs in the female to fertilize them. Female Peripatoides novaezealandiae then, however, do not lay eggs like many other species, but retain them for 9-12 months during which the embryos are nourished through a special tissue in the female body’s uterus that has been likened to a placenta.
Eventually, only a very small number of young are born, but considering the small size of the maximally 5.5 cm long mother, her whitish babies measuring almost half their mother’s size, are gigantic. These delicate, small and secretive animals (also known as “velvet worms”) have apparently been around for at least 400, if not 500 million years and have survived untold geological, meteorological and cosmic upheavals unchanged – a truly remarkable feat. And I (to be honest, it was the video camera we had installed above the terrarium) witnessed the birth of one! Certainly not at all an everyday event.
© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2018.
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