To celebrate Father’s Day in June, let’s take a look at some unique fathers amongst marine creatures! Typically parental care is categorized into three groups: biparental—both mom and dad care for their offspring; maternal—mom provides most of the care; paternal—dad provides most of the care. In mammals and birds, biparental and maternal care are the dominant parental style across different species. Fish, however, demonstrate an opposing pattern with a greater proportion of species providing paternal care.

One of the most well known examples of parental care are seahorses. Despite their unique appearances, seahorses are considered “fish!” Seahoress inhabit tropical or temperate coastal waters and are distinguished by their upright bodies, curled tails, and horse-like snouts. Seahorses are further characterized by the paternal care that males provide via a brood pouch, also called “male pregnancy”. During mating, the female transfers her unfertilized eggs into the male’s brood pouch. The male then fertilizes and incubates the eggs. As part of the incubation process, the male will regulate the oxygen and salinity levels in the pouch and provide nutrients to the eggs. Male seahorses can carry up to 2,000 eggs at a time in their brood pouch. Incubation lasts anywhere from 10 to 25 days, depending on the species. Other close relatives of the seahorse—such as pipefish and sea dragons—also exhibit paternal care in a similar fashion. Male pipefish and sea dragons carry their offspring attached to the underside of their tail. Another obscure and unusual style of paternal care is mouthbrooding. This behavior has been observed in cardinalfish, sea catfish, and jawfish. In mouthbrooding, the males carry all of their eggs inside their mouth, with some housing the young juveniles in their mouths for a short period even after hatching is complete. 

Although male pregnancy and mouthbrooding can offer greater protection from predators, these methods also have drawbacks. First, for male pregnancies in seahorses and mouthbrooding in cardinalfish, sea catfish, and jawfish, the mated couple quite literally “put all their eggs in one basket”. If the male dies, so does the entire clutch of eggs. Mouthbrooding, in particular, can be even more detrimental to a father, as he often foregoes eating while carrying the eggs. This may decrease his fitness for future reproduction. Nevertheless, the success of these paternal care strategies has allowed these species to persist.

While we celebrate and appreciate the care of these special, ocean-based dads, please also take time to reflect on the care your father and/or father-figures have provided!

We are swimming into another summer, and this June brings us up close to a spotlight species that’s got bite! On June 17th we are throwing this reptile into the ring as we celebrate World Crocodile day. There are around 16 species of true crocodiles belonging to the family Crocodilia, which is shared between crocodiles, alligators, and caiman. Unlike alligators, crocodiles have longer, narrower jaws, an olive green body, and a longer evolutionary history going back 90 million years! Your typical crocodile is born with a mouthful of conical teeth, not serrated teeth like a shark, perfect for ensuring an inescapable and deadly bite. With nostrils, eyes, and ears above water, a crocodile can lurk with its body out of sight until the moment of ambush, when it slices through the water with a muscular, plated tail at 20 miles per hour speeds. With a perfect attack and a near-perfect defense of bony-plated armor from snout to tail, they are one of nature’s fiercest predators. So what is driving them to the point of vulnerability that merits an international holiday?

Unfortunately, crocodiles face a variety of human threats all around the world. Direct threats such as hunting and habitat loss are the greatest concern, while pollution and bycatch mortality have exacerbated the population declines of many crocodile species. Recent studies have shown that the absence of crocodiles will result in a 38% decrease in functional diversity. The unique ecological services provided by crocodiles will be lost, such as burrowing, which provides habitats for other species, keeping the food chain in line, and transporting nutrients. Unfortunately, some of the most unique and contributive species are critically endangered, such as the striking Gharial, a crocodile known for its long and skinny snout. In order to slash these endangered numbers, we celebrate a day focused on the conservation and care of crocodiles. Learning and contributing to habitat restoration and conservation is the most important thing we can do today to safeguard at-risk species. Advocating for the continued preservation of natural reserves, national and state parks, and public lands works to protect beautiful habitats and the amazing creatures that dwell there. Celebrate World Croc Day by helping to spread awareness about these impressive animals, their struggle against extinction, and how land conservation is the key to reversing the damage done by humankind!

Summer is a busy time for our oceans, and not just because of vacationers flocking to beaches and resorts. Warmer waters and longer days set marine life into motion as well, with huge migrations occurring across a number of species, big and small, all throughout the world. 

Many marine animals follow seasonal migration patterns, spending their summers in one region and their winters in another. They generally migrate in search of food or places to produce offspring. The warm waters and gentle summer currents are ideal for young to grow in and acclimate to their pod, school, or bale. Turtles are a hallmark of summertime marine migrations, as species all around the Northern Hemisphere begin nesting their eggs in late spring. Thousands of loggerhead turtles arrive each year at the Yucatán Peninsula in Mexico and in Palm Beach, Florida, where eggs are laid and hatchlings race from the sand to the surf. A fascinating study found that female sea turtles use the Earth’s magnetic fields to return to and nest at the same beach they were born on! The unique signature of their birthplace is “imprinted” on them as hatchlings, believed to be a function of magnetic particles in their brains. Similarly, leopard sharks crowd the shallows of La Jolla, California, to raise their young and incubate their eggs in the warm water and sand. In some cases, feeding and breeding occur at the same time and in the same place. Right whales, for example, travel to the Gulf of Maine and Acadia National Park to feed on abundant krill and salmon, which also migrate into the gulf at the start of the season. Some animals seek out cold waters come summertime. Humpback whales are one such example, as they migrate over 4,000 miles from tropical seas to polar seas to feed on krill before returning to the warm waters for winter breeding. Blue whales do the same, and their northward migration passes San Diego, California, every year, a spectacle that offers the chance to witness the largest animal on Earth.

Summer in the northern hemisphere is winter below the equator, though this does not mean that the seas in the southern hemisphere are any less active. In fact, one of the most famous marine migrations occurs in South Africa between May and July. In what is often called the “Greatest Shoal on Earth,” billions of sardines flee from dolphins and sharks along the coasts, creating the largest shoal in the world! 

Like so much else in the aquatic world, climate change has affected the migration patterns of marine life. Summer water temperatures have begun to arrive in spring, which causes animals to prematurely initiate their reproductive periods. Wind and ocean currents are stronger in the spring, making it more challenging for young to survive. Marine heat waves are also increasingly common, and these cause more toxic algal blooms, which were covered in our May newsletter. Harmful algal blooms and dead zones can drive marine life away from their regular breeding grounds. As a result, animals have had to seek out new bodies of water to migrate to. Given how critical migration is to marine species, it is equally vital for us to spread awareness about the issues affecting it.