Ovoviviparity – Top 10 examples of ovoviviparous animals (video and pictures)
What do snakes and sharks have in common? Some of species of these animals are ovoviviparous. If you haven’t heard the term ovoviviparous before, don’t worry – most people haven’t!
We tend to divide the animal kingdom into viviparous and oviparous animals. Viviparous animals are nearly all mammals. These animals develop an embryo in a womb and give birth to live young. Birds and most reptiles, on the other hand, are oviparous. Oviparous animals reproduce by laying eggs. The young develop in the egg and obtain nutrients from the yolk before hatching.
Caught between these two reproductive methods are the unique and rare ovoviviparous animals – a combination viviparous and oviparous. Unlike oviparous animals, which lay eggs and then leave them to hatch on their own, ovoviviparous animals lay eggs internally. The eggs stay inside the parent’s body until they are ready to hatch. Once hatched the animals feed internally and young are born live.
There are different types of ovoviviparous animals, and they can be found all over the world. Let’s look at some examples…
1. VIPERS
A quick internet search will give you a plethora of videos of snake eggs hatching. We happen to be quite obsessed with Snake Discovery’s educational snake hatching videos (even their rescue alligator names Rex). But did you know that not all species of snake lay eggs? That’s right, some species are ovoviviparous!
Most vipers are ovoviviparous. A famous member of this group is the rattlesnake. Brood size varies based on species, but typically 5 to 20 young are born at once. Females usually only reproduce once every two to three years. The young do not stay with their mother long and are off to fend for themselves shortly after birth. Newborns have both functioning venom glands and fangs at birth.
2. ANACONDA
The world’s heaviest snake is ovoviviparous. Because of their huge size, anacondas give birth to much larger broods than other ovoviviparous snakes. Females routinely give birth to 20-40 young, but broods of over 100 have been reported. The newborns are generally less than three feet long and head off on their own.
3. SHARKS
A fascinating fact about sharks is that pups can develop in all three reproductive categories- oviparous, viviparous, and ovoviviparous. Great white sharks, nurse sharks, and tiger sharks are some examples of ovoviviparous shark species. With these species, the first shark to hatch will consume the other shark fetuses and their yolk sacs. This form of fetal cannibalism helps ensure only the strongest pups survive, generally litters are only 1-8 pups.
4. RAYS
Unlike sharks, which exhibit a wide array of birthing strategies, almost all species of rays are ovoviviparous. It is highly unusual for such a huge array of species (over 600 known species of rays) to be dominated by ovoviviparity. Manta rays birth 1-2 pups every other year.
5. SEAHORSE
In an interesting twist on ovoviviparous reproduction, it is the male seahorse that incubates and hatches the young. The female deposits her eggs in the male’s brood pouch. Once the eggs are fertilized, they’re embedded in the male’s belly pouch, where they’re incubated and nourished before hatching. Upon hatching the fry resemble miniature adults. The baby seahorses remain in the pouch as the male slowly adjusts them to the salinity of the surrounding water. They are released into the water column where they drift about in open water as juveniles. Depending on the species, up to1000 eggs may release at a time.
6. GUPPIES
Guppy fish are extremely popular aquarium fish as they are affordable, easy to care for, and come in an array of colors. Unlike most ovoviviparous fish, which give birth to a few young at a time, guppies can give birth to as many as 200 fry at a time. Female guppies can store male sperm for up to 10 months, allowing them to give birth to several broods without having necessarily mated again.
7. FROGS
While the majority of frog species lay eggs, a few species are ovoviviparous. In the golden coqui frog you can observe the froglets moving around in the mother’s reproductive tract before she gives birth. In at least one South American species, the Darwin’s Frog, the young develop in the vocal sac of the male, while in some Australian frogs they develop inside the mother’s stomach.
8. FLIES
Some species of fly, especially the carrion flies, the larva hatch before being laid. This is most common in flies whose larva depend on being immersed in a food source immediately. By hatching the eggs before they’re laid the mother fly can ensure that she deposits the larvae on a fresh food source.
9. SLOW WORM
While easily mistaken for snakes, the slow worm is a legless lizard. The young are born while still in the egg, which has a very thin, transparent shell. They break the shell immediately after the egg is laid, which indicates that they have developed extensively before being laid.
10. Chameleon
While most of these color-changing reptiles are oviparous, some species are ovoviviparous. In these species, there is typically a five-to-seven-month gestation period. Each young chameleon is born within the sticky transparent membrane of its yolk sac. The mother presses each yolk sac onto a branch, where it sticks, and the young chameleon immediately breaks out of the egg. Females can have up to 30 live young from one gestation.
Reference and further reading/viewing:
10 examples of ovoviviparous animals video!
Ovoviviparity in the animal kingdom, Top 10 examples of ovoviviparous animals
