Rigor Vitae: Life Unyielding

Monday, March 13, 2006

PATERNITY AND PATERNALISM

No vertebrate order exhibits a wider range of reproductive strategies than do the frogs. Like all amphibians, their eggs have no shells and are vulnerable to desiccation. In open water that is not a problem, but there they are subject to predation by fish and other animals. It is the tension between these two dangers that has led frogs down so many different reproductive paths. There are frogs that lay their eggs in burrows, on land, on leaves, in foam nests, and in every imaginable kind of water vessel. Members of several families carry their eggs on their own backs in several different ways—in fact parental care is widespread and varied among frogs. The females of the two species of the Australian genus Rheobatrachus, which probably went extinct in the 1980s, actually brooded their eggs in their own stomachs. Parental care has probably been best documented among the Neotropical poison frogs of the family Dendrobatidae. A small number of eggs are typically laid on a leaf on the forest floor, where they are guarded by one or both adults, who urinate on them periodically to keep them moist. Upon hatching the tadpoles are taxied to water on the back of an adult. Probably the best known member of this family is the Strawberry Poison Frog (Dendrobates pumilio) of Central America's moist Caribbean lowlands. Within their range these aptly named ½-inch long amphibians are extremely common, and their life history has been documented time and again in the literature for well over a century. The male guards the eggs, and the newly-hatched tadpoles are transported, one at a time, to the tanks of a pre-selected bromeliad, where they are deposited. The female returns regularly to lay an infertile egg in each tank, for the tadpoles to feed upon. The original accounts described the male carrying the tadpoles to the bromeliad, and for many decades naturalists (myself included) simply took the older literature at its word, and credited Papa Frog for the effort. The fact that the she-frogs had been doing the actual hauling went unnoticed until the 1980s. The sexual dimorphism of this species is far from obvious, but the males can be distinguished from the females by their slightly smaller size and beefier first two fingers. Most of what we know about the world we know from being told. If we questioned it all, we'd have time for nothing else. Still, having an open pair of eyeballs can be very rewarding.
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ASCENSIÓN—STRAWBERRY POISON FROG & TADPOLE (2005) acrylic 40" x 15"

9 Comments:

Anonymous Karmen said...

"The female returns regularly to lay an infertile egg in each tank, for the tadpoles to feed upon."

Woah... now there are some girls who have learned to put their cycle to good use. I'm not sure if I should be disgusted or jealous.

"Hey, kids! Dinner's ready!"

6:32 AM  
Blogger cpbvk said...

Ha! Actually, it's not that different from provisioning your young with a big yolk sac.

7:22 AM  
Anonymous bev said...

Fascinating piece and a wonderful painting, Carel!

3:36 AM  
Blogger Senescent Wasp said...

This comment has been removed by a blog administrator.

7:53 AM  
Blogger cpbvk said...

Bev: Thanks so much!
Senescent Wasp: Your comment appears to have senesced with you.

8:48 AM  
Anonymous Walter Brameld IV said...


"Woah... now there are some girls who have learned to put their cycle to good use. I'm not sure if I should be disgusted or jealous.

"'Hey, kids! Dinner's ready!'"


When you think about it, it's no more disgusting than babies drinking murky liquid oozing from modified sweat glands. (That's not to say it's not disgusting....)

4:50 PM  
Blogger Online Degree said...

It is interesting to see how nature takes care of itself.

12:14 PM  
Blogger Online Degree said...

and perhaps even more interesting to see how we (humanity) have chosen to try harder and harder to take care of ourselves without relying on nature as much. Just something interesting to think about...

12:15 PM  
Blogger cpbvk said...

Walter: Ha! It really is fascinating to look at the many different strategies creatures have come up with for giving their vulnerable young an edge.
O.D.: Thanks for your comments. I agree that we've tried harder and harder to take care of ourselves, but whether it's obvious to us or not, we're every bit as dependent on nature as we ever were.

8:51 AM  

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