Tag: Reproduction

Posted on

Twisted naval string

Twisted naval string:

Forty turns of jelly and

contrary vessels.

 

Break benefits both before

severing the thread of life.

 

The umbilical cord has traditionally been cut (or at least clamped) 15-20 seconds after birth but increasingly research suggests that a longer delay before cutting is beneficial for both term and pre-term infants.

For term infants a delay of 30-60 seconds can increase haemoglobin levels at birth and iron stores in the first months of life. In preterm infants a delay can improve transitional circulation, result in the better establishment of red blood cell volume and decrease the need for blood transfusions.

A delay before clamping and cutting is therefore recommended by both the World Health Organisation and the American College of Obstetricians and Gynaecologists.

This sciku is actually an example of a tanka – the first two verses of a traditional renga, where haiku originate from. Learn more about haiku, renga and tanka here.

Posted on

Plenty of fish

Plenty of fish yet

male voles choose monogamy

… but do their partners?

 

Monogamy is relatively rare in the animal kingdom, with extra-pairs matings happening a lot more than you might think. Males in particular are thought to gain the most from polygamy by being able to sire multiple offspring, whilst females may gain from monogamy through defence or paternal care of their young.

Yet despite having access to multiple females, male prairie voles choose to form exclusive pair bonds with individual females (Blocker & Ophir, 2016). In contrast,  female prairie voles readily engage in promiscuous mating (Wolff et al, 2002).

So why (under laboratory settings) are male prairie voles monogamous whilst females are promiscuous?

Blocker & Ophir, 2016 argue that one explanation could be that the costs to males of trying to hang on to multiple females at once are too great, and that male prairie voles gain the most by aggressively monopolising just one female. Females on the other hand have nothing to lose from polygamy so will mate with other males if the opportunity presents itself.

In prairie voles it seems that monogamous behaviour may be male-driven.

Posted on

Paternal spider

Paternal spider

to die at the ‘little death’,

worthy sacrifice.

 

Mating is a dangerous game for males of many species of spider, with females often winding up with a nutritional meal to help fuel egg production. Taking their paternal responsibilities to an extreme, male dark fishing spiders spontaneously die during copulation. Females that are allowed to eat their dead mates produce a greater number of offspring, of a greater size and with an increased survivorship compared to females prevented from eating their mate or females provided with an equivalently sized cricket. It seems cannibalism isn’t all bad. Schwartz et al, 2016.