晨讀英語(yǔ)美文60篇53 Seahorse Fathers Take Reins in Childbirth
[00:04.96]It’s true that male seahorses never play catch with their children
[00:11.31]or help them with their homework.
[00:13.28]But they do outdo human dads on one count.
[00:16.89]Male seahorses undergo pregnancy and give birth to their sons and daughters.
[00:23.00]The trait is unique in these strange and fascinating fish
[00:26.07]that inhabit tropical and temperate coastal waters worldwide.
[00:30.00]Seahorses, which range from less than an inch to a foot in length,
[00:35.04]have evolved a series of unusual adaptations.
[00:38.33]They are such an unusual looking fish that
[00:41.61]people sometimes don’t realize they’re real fish.
[00:44.88]The male seahorse has a pouch on its stomach in which to carry babies—
[00:49.80]as many as 2000 at a time.
[00:52.77]A pregnancy lasts from 10 to 25 days depending on the species.
[00:57.96]The reproductive process begins
[01:00.47]when a male and a female seahorse do daily predawn dances
[01:05.29]intertwining their tails and swimming together.
[01:08.25]Eventually they engage in a true courtship dance,
[01:12.29]which can last as long as eight hours.
[01:15.02]It ends with the female depositing her eggs in the male’s pouch.
[01:19.39]The eggs hatch in the pouch.
[01:21.81]The father cares for the young
[01:23.57]as they grow regulating the water salinity in the pouch to prepare them for life in the sea.
[01:29.78]When the tiny seahorses are ready to be born the male undergoes muscular contractions
[01:36.35]to expel the young known as “fry” from the pouch.
[01:39.95]While seahorse dads go the extra mile to give birth
[01:43.68]the parents do not provide their tiny offspring with any care or protection
[01:48.93]after they are born.
[01:50.34]Infant seahorses are susceptible to death from predators
[01:54.30]and being swept into ocean currents
[01:56.69]where they drift away from feeding grounds rich in microscopic organisms.
[02:01.39]Fewer than five infant seahorses in every 1000 survive to adulthood
[02:06.76]which helps explain why the litters are so large.
