While seahorses certainly are a unique-looking fish, that’s hardly their most unusual trait. Seahorses and their relatives, pipefishes, are the only family of fish in which the males become pregnant and give birth.The process begins with males seeking out the largest females, who provide the largest size and greatest number of eggs. The pair swim together, “hold tails” and “dance” for several mornings. Then, an 8-hour courtship dance leads to the actual mating.
The Marine Science Institute's monthly column, Science and the SeaTM, is an informative and entertaining article that explains many interesting features of the marine environment and the creatures that live there. Science and the SeaTM articles appear monthly in one of Texas' most widely read fishing magazines, Texas Saltwater Fishing, the Port Aransas South Jetty newspaper, the Flour Bluff News, and the Island Moon newspaper. Our article archive is available also on our website.
If being a “blue blood” is a sign of royalty, then horseshoe crabs may be the kings and queens of the sea. In fact, their unique blood is one reason they have survived for more than 450 million years.
Horseshoe crab blood is actually gray-white to pale yellow most of the time because it rarely carries much oxygen. But when oxygenated, horseshoe crab blood is blue because it contains the copper-based compound, hemocyanin, instead of the iron-containing hemoglobin that gives most other creatures red blood.
Horseshoe crabs are known as “living fossils” because they have survived on Earth for more than 450 million years. Although they have evolved in small ways over the millennia, they haven’t changed nearly as much as the world around them. Over the years, horseshoe crabs have seen the rise and fall of the dinosaurs, lived through the rise of the mammals and survived three major extinctions, including a huge one 250 million years ago that wiped out about 96% of marine creatures and 70% of large land animals.
This poison is called tetrodotoxin, a word coined after the puffer fish’s scientific name. It’s a potent neurotoxin that can kill even humans when ingested. Though this toxin was first identified in puffers, the fish don’t actually make it themselves — in a way, they borrow it.
When threatened, puffers puff themselves up by gulping down water and pumping it into their highly expandable stomachs, making their bodies difficult for predators to swallow. One spiny puffer species, called the balloonfish, swells to about 3 times its usual volume. Most of that increase is thanks to the stomach, whose many folds let it expand by 50 to 100 times! At the same time, hundreds of sharp spines all over its body stand erect.
What is the greatest size and age a living thing can achieve? Seagrass meadows may hold the answer.
Seagrasses are flowering plants that have adapted to live submerged in the ocean. Although there are only about 60 species, they cover a vast amount of the world’s temperate and tropical coastal areas.
Watch a stingray glide over the sandy sea floor and you can tell it’s in hunting mode — but the tricks the ray is using to search for prey may not be so obvious.
A stingray’s eyes are located on top of its wide, flat body, while its mouth is on the underside. This may not seem like the best design for a fish that has to scan the murky bottom for hidden clams and crustaceans. Luckily, rays are endowed with remarkable sensory abilities that make them ace hunters.
In Antarctica’s coastal waters, a group of perch-like fish called icefish dominates. The water column in these frigid seas is filled with tiny ice crystals, and fish are constantly exposed to ice through their gills and skin. They even ingest ice crystals when they eat and drink.