By Julie Etra
There is enormous variation in the animal, and even the plant, kingdom when it comes to reproduction. Parenting and sexual roles are an even more complicated topic, with lots of shades of gray. So, let’s start close to home with the fish of the waters, reefs and bays of Huatulco:
The male seahorse gives birth. These animals are found in shallow tropical waters and occur in the reefs around Huatulco. Seahorses aren’t really good swimmers – they swim upright and typically hide in sheltered coral reefs and rocks. They are closely related to pipefish, which swim horizontally, and both have a bony exoskeleton instead of an internal skeletal system. The male has a pouch; when seahorses mate, the female deposits up to 1,500 eggs in this pouch. Incubation takes up to 45 days, and the very small baby seahorses emerge fully developed. The young are released into the water and the male often mates again within hours or days. They are not hermaphrodites, as the sexes are separate and remain so.
And what is hermaphroditism?
A hermaphrodite is “an organism that has complete or partial reproductive organs and produces gametes normally associated with both male and female sexes. Many taxonomic groups of animals do not have separate sexes.” Male gametes are sperm, female gametes are eggs. In summary, they start with full male and female capabilities, and potentially change from one to the other depending on the circumstances, which can be myriad.
Protogynous hermaphrodites are born female and at some point in their lifespan change their sex to male. As the animal ages, it shifts sex and becomes a male animal due to internal or external triggers. Protogyny is more common than protandry, where the male becomes female.
Hermaphroditism is a fairly common occurrence among coral reefs species, particularly the wrasses, parrotfish, gobies, and some species of eels.
These are very common around the reefs of Huatulco; we have the ubiquitous rainbow wrasse, Mexican hogfish, and the distinctive rockcrawler wrasse. Their reproductive strategies are complicated. The rainbow wrasse has two types of males and two methods of reproduction. The Mexican hogfish starts life as a female, and after having achieved a larger size, becomes a functional male. The males gather in groups to perform competitive displays to attract females and defend their reproductive territories; the groups are known as “leks” and the displays as “lekking.” (Other species, notably the sage grouse, also gather in groups to attract their “harems” for mating.)
We have these fish in the Bahías, but they are not common. If you are snorkeling or scuba diving, you might a crunching sound – the parrot fish are dining on coral. What makes these fish unique is that they can change their sex throughout their lifetime. Primary males are fish that are born male and stay male, while secondary males are males that are born female and become male when they reach sexual maturity.
Gobies are members of a very large fish family; their habitat is the shallow waters around the reefs of Huatulco. They have mommies and daddies. Daddies protect the nest from predators, take care of the eggs by fanning the eggs to increase the availability of oxygen, while mommies keep the house nice and tidy. When the females quit their household duties, the eggs are consumed by the males. Some species of gobies can change their sex, and their genitalia will change to follow suit. Sex change can occur over days or weeks and from female to male if the dominant male has died.
We have morays and zebras in our reefs. Some species are hermaphroditic, starting their mature life as males, changing sex later to females, but some are both female and male at the same time.
These fish don’t occur in our reef systems here but they are too interesting to not mention. Made famous by Nemo (not a gender-accurate portrayal!), they live symbiotically with anemones, each helping the other to survive and thrive. The sea anemone protects the clownfish from predators and provides food. The clownfish in turn defends the anemone from its predators and parasites. Clownfish schools are female dominated; the females carry both female and male reproductive organs.
The large female fish is dominant, but upon her death the dominant male gains weight and changes sex. While she is still in charge, she mates only with the breeding male. The rest of the community comprises sexually immature males, or ‘”bachelors.” Changing sex is determined by hormones that cause the testes to disappear and trigger the development of the ovaries. Parenting? Both the male and the female maintain and guard the eggs once they are laid by the female.
Here is another super odd one, a species that does not occur on our beautiful coast, but is just too interesting not to mention – the anglerfish. To get a look at them in action, go to http://www.livescience.com/48885-rare-anglerfish-video-footage.html.
These fish dwell at great depths, below 984 feet, in Monterey Canyon off the central coast of California. The male is tiny compared to the female. Once he finds a willing female the male bites and latches on to her belly. Their tissues fuse, the male wastes away, and all systems become one. The male’s only purpose is to provide sperm, while the host female becomes a bizarre self-fertilizing hermaphrodite.
For plants, the phenomenon of no mommies or daddies needed is perhaps more common than you might realize.
These include Hens and Chicks and Mothers of Thousands. These easy to grow succulents are very common in gardens and nurseries around Huatulco, as well as higher up in temperate climates, including San José del Pacifico, well above Pochutla on the route up the mountains to Oaxaca. Although they flower and can produce seed, they more commonly produce new plants with their own root systems, e.g. vegetative reproduction. Thanks to some local friends, I have a lovely Mother of Thousands in our Huatulco garden. It is also known as the “devil’s backbone,” “alligator plant,” or “Mexican hat plant,” and is native to Madagascar. Each plantlet has its own root system, ready to drop off from the momma/poppa plant and establish a new plant.
We all know the Nopal plant, of which there are many types in Mexico and the southwest United States. Also known as prickly pears, these cacti prefer warm, dry or seasonally wet climates like our own selva seca (seasonally dry tropical forest). They also produce a fruit, known as a “tuna” (one of the delicious flavors of the shaved-ice nieves available in the Huatulco Organic Market). The tuna contains seeds which readily geminate. But the big pads, called pencas, that are sliced and diced and commonly cooked in Mexican cuisine, can become detached and roll downhill, or attach to and detach from cattle and wildlife, and establish new roots at the base of the penca – hence new plants, no seeds. Voila.
Ah papayas, that yummy tropical fruit, whose origin is the southern coast of Mexico, have male and female flowers on separate plants, but also both on the same plant. The male plant actually possesses female parts but they are not fully developed or functioning. However, with rising temperatures the plant can generate a fruit-producing female. Female plants can produce fruit, with seed if pollinated, or without seed if not pollinated (think unfertilized chicken eggs).
Hermaphroditic papaya flowers have both functional male and female flowers. They are capable of producing fruit and don’t require pollination. However, like male papayas, they can change gender. They may switch to being male during hot weather, or to female after being topped.
Despite our expectations of neat and not-so-neat nests filled with eggs, and mommies and daddies hatching the eggs and feeding the squawking hatchlings, there are species that do not really share parenting, and there might even be a few instances of hermaphroditic reproduction.
These large, colorful, flightless birds are native to Australia and are related to emus and ostriches. The cassowary breeding season occurs in May and June when the male prepares the nest, which consists of a pile of leaves and other debris, and the females lay three to eight large eggs. The male then sits on the nest for 50-52 days, adding or deleting litter in order to regulate the nests’ temperature. After the chicks emerge, they remain in the nest for about nine months while daddy protects them. The female is not involved in raising the chicks, rather going off to lay more eggs in the nests of several other males.
And last, hens turning into roosters? Is this possible? Even in Huatulco? Apparently very rare, but it has been documented. Consider the case of Gertie the hen, who hailed from England. In 2011 she suddenly stopped laying eggs, grew a characteristic rooster comb, and began acting like a rooster. This is due to the unique physiology of chickens. They have one ovary and an undeveloped sex organ that can become a testicle or an ovary but remains dormant unless environmental triggers and subsequent male hormone production result in its morphing into a rooster appearance. Although it cannot reproduce, it develops behavior characteristic of roosters, including aggressive territorial behavior and crowing at dawn. (Of course, if you’ve ever raised chickens, you know they crow at dawn, midnight, lunchtime, whenever they damn well feel like it!)
“Variety is the spice of life,” ain’t it grand?!