Manta rays do not lay eggs; they give birth to live young. These large rays belong to the class of cartilaginous fish called Elasmobranchs, which also includes sharks and skates. Their reproductive process results in a fully developed pup that is immediately independent upon birth. This slow reproductive rate makes manta ray populations vulnerable to environmental pressures.
The Direct Answer: Live Birth
Manta rays use a reproductive method known as aplacental viviparity, sometimes referred to as ovoviviparity. This means the young develop inside the female’s reproductive tract, but a true placental connection does not form to nourish the embryo directly from the mother’s bloodstream. This process differs significantly from the oviparity seen in many skates and some sharks, which involves females laying eggs encased in leathery shells in the water.
The female manta ray carries her young internally until they are ready to be born fully formed. The reproductive tract provides a protected environment for the developing pup, offering a much higher chance of survival than an egg case left exposed in the ocean. This adaptation ensures the young are robust enough to face the challenges of the open ocean immediately after birth.
Inside the Mother: Gestation and Development
The internal development of a manta ray pup takes approximately 12 to 13 months. Initially, the embryo is enclosed within an egg case inside the uterus, drawing nutrients from a large yolk sac. As the embryo grows, the yolk sac depletes and the egg case dissolves.
The developing pup then switches to a specialized form of internal feeding. The uterine wall secretes a nutrient-rich fluid known as histotroph, or “uterine milk.” This fluid, packed with proteins and lipids, is absorbed by the pup, allowing it to grow significantly before birth. Typically, only one pup develops at a time, though the birth of twins is possible, but rare.
Life After Birth: Manta Pups
Manta ray young, known as pups, are born large and immediately independent. A newborn reef manta ray can measure between 150 to 167 centimeters (about 5 to 5.5 feet) in disc width, and oceanic manta pups can be even larger. The pup is born with its pectoral fins rolled up like a tube, which unfurls shortly after exiting the mother.
These large newborns must quickly find safe areas to grow, often seeking refuge in shallow, coastal nursery grounds. These habitats provide protection from larger predators and offer an abundance of food, allowing the young rays to double their size within their first year. Females often only give birth to a single pup every one to three years.