Knowing Little Ray to be brave and young,
Mama Ray managed to hold her tongue.
After all, her boy would never ever know
what he could do without giving things a go.
(The Amazing Flight of Little Ray)
In this month of motherhood, Mama Ray tells about baby stingrays being born, survival to adulthood after baby stingray birth and how long stingray babies stay with mother stingrays.
Pregnant stingrays move to low-risk areas for baby stingray birth. In The Amazing Flight of Little Ray, Mama Ray represents love, care and protection. Safety at birth gives little stingrays a good start. Birthing typically is annual.
Stingrays are born live. They are folded and spindle-shaped upon exiting the cloaca. Their spines are flexible. A sheath covers them to cushion the females during delivery. The sheath sloughs off shortly after birth.
Birth usually occurs at night. Stingrays in the wild are nocturnal. As the mother stingray goes into labor, males assemble to impregnate her immediately after delivery. The gestation period averages 9 to 12 months.
The first pregnancy often gives birth to one “pup”. As females mature, there can be up to twelve pups in a “litter”. Female deep-water ocean stingrays and mantas leave at birth. Males depart immediately after mating.
Female stingrays may safeguard offspring until they mature. Discus fish also care for their young. Depending upon the species, stingray maturity is achieved between 1 and 5 years of age. Females progress faster than males.
Newborn stingray pups sink to the ocean floor. They unfold and quickly begin practicing their swimming. It takes a few days for them to develop a consistent and powerful stroke. This accomplished, they begin hunting.
Female stingrays and sharks have a single reproductive opening. Called the cloaca, it serves as the channel for birth, feces and urine. Bony fish have no cloaca. It is common in birds, reptiles and amphibians.
Tough Love? Male stingrays and sharks have two reproductive organs. Paired claspers extend toward the tail from each pelvic fin. One appendage is used for each mating session. Painful spurs grasp the female for copulation.
Claspers deposit sperm into the cloaca. More than one male may chase down a willing or unwilling female. During copulation, the male arches his back and stretches a clasper forward to fertilize eggs in the female cloaca.
Tonic immobility may aid in reproduction. This temporary state of paralysis may be induced when sharks and rays are flipped over. Enhanced by belly rubs, this 15-minute trance-like state helps render sharks cooperative.
Soft touch? Science writer Mary Bates brought shark “hypnosis” to Wired. Humans should not rely fully upon this natural calming technique. Aroused sharks quickly regain normalcy. Tail-whips or bites may be reality-checks.
Survival to Adulthood
Fish make no facial expressions. Actions give clear signs of rage or calm. Children see hints of motherly care and worry in Mama Ray. She worries about Little Ray's daredevil risk-taking to soar above all Flying Stingrays.
Fish seldom give warnings. Like mama dogs, mama rays may charge at intruders. Both mothers are equipped to defend their pups. Stingrays wield venomous stinging barbs. Mama dogs growl and brandish fierce fangs.
Wild at heart? Baby sharks receive no parental care. Some arrive live, by viviparous, placental birth. For ovoviviparous species, fertilization is internal. Eggs with shells, membranes or envelopes hatch within the parental body.
Fish can suffer life-threatening egg binding. Obesity, malnutrition, stress or small body size may result in failure of eggs to exit the reproductive tract or be absorbed. Deadly infection may progress with egg impactions.
Most fish are oviparous. They hatch from eggs. Fertilization is external. Embryos develop within laid eggs. Some fish are hermaphrodites with both male and female sex organs. Others can alternate as males or females.
Female sharks seek safe locations to lay eggs. Sharks in the Heterodontidae family, including Port Jackson, Bullhead and Horn Sharks lay spiral-shaped egg cases. They harden in place after females push them into crevices.
Semelparous animals reproduce once. Male octopuses, squid and cuttlefish die after egg fertilization. Females live long enough for birthing. Most fish are iteroparous with multiple reproductive cycles over their lifetimes.
Bony fish reach adulthood in stages dissimilar to cartilaginous fish. They are called larvae while sustained with yolk-sacs. They become fry once they can feed themselves. Fingerlings have working fins and can begin hunting.
Calling the Shots? Male seahorses fertilize and carry eggs in pouches. Fully developed fry are released into independence. One type of seahorse mates for life. Male ariid catfish orally incubate eggs until the fry are able to swim.
Stingrays give aplacental, ovoviviparous birth. Viviparous sharks have placentas for nutrition and waste exchange with the mother. Their mammal-like umbilical cords attach the embryo to the placenta.
Ovoviviparity is more aptly described as histotrophic viviparity. Uterine histotrophic secretion provides sustenance after yolk depletion. Offspring are highly developed at the time of live delivery.
Internal shark embryos may consume smaller embryos or eggs. From several eggs, one or two of the most fit pups is born. In sharks with two uteruses, intrauterine or interuterine embryophagy and oophagy may occur.
Egg-laying sharks produce 10 to 200 eggs. Eggs are protected by leathery cases called “mermaid's purses”. Yolks sustain the embryos to an advanced stage of development. They hatch as fully-developed “pups”.
Being in the wrong place might end poorly. Some mother sharks devour their young. Large sharks and other predators dine on shark pups and smaller rays. Low birth and survival rates contribute to losses set forth in No fishing.
Giant mantas use size as defense. They can make cow-like head butts or body slams. They have no venomous stingers. Little is known about these large, primitive fish in the Mobulidae family of ocean rays and devil rays.
No kittens roam seas. Oviparous catsharks hatch as “pups”. Catsharks (Scyliorhinidae) and dogfish (Squaliformes) look similar. Ovoviviparous dogfish lack the anal fins present in catsharks.
The best-known cubs of ocean life are polar bear babies. Humans are their only predators. Sharks in frigid polar bear country hunt at great depths. Bears catch seals from land or from ice floes near the water surface.
Fathers play important roles. Few fish and no mollusks are born into the ocean as fully-formed miniature adults. Children on land may get help from both parents. Sea creatures are lucky to have any oversight from one parent.