7 Sea Star Facts
Article by: Danielle Schofield
With regular appearances from the seabed to the big screen’s cartoons, the starfish is a widely-known and well-loved sea creature, especially with children. However, it’s not actually a fish and for that reason, marine biologists prefer to call the invertebrate a sea star.Most people know that sea stars typically have 5 (or multiples of 5) identical arms. These arms extend from a center body in a star shaped arrangement, and they travel across the seabed slowly with suction-cup “tube feet.”Here are seven more fun facts on sea stars you can use to impress your kids/friends/fellow divers the next time you spot one: #1 – Sea stars can reproduce sexually and asexually. During ideal conditions, sea stars group together to spawn, and have sexual organs, or gonads, in each arm. Males and females release thousands of sperm and eggs into the water and hope they meet for fertilization. Asexual reproduction usually occurs as a result of dismemberment. #2 – Sea stars have unusual stomachs. It pushes its stomach through its mouth, digesting food while the stomach is outside its body. #3 – Sea stars don’t have a brain or blood. Instead of blood, they have a seawater vascular system. In the place of a brain, the sea star has an intricate nervous system. #4 – Sea stars can change gender. Depending on availability of food and the water temperature, a sea star can change its gender to whichever one is best suited for its environment. #5 – Sea stars can regenerate body parts. A new sea star can regenerate if part of it becomes severed. Regeneration is a less than ideal way to reproduce because it doesn’t allow for DNA diversification. #6 – The female sea star can produce millions of eggs. Other animals eat most of the eggs, meaning only a few will ever become adults. #7 – They have an eyespot at the end of each arm. Their vision is primitive, and they can only sense movement, light and dark.
Why Touching Is Never Okay
By Jessica Vyvyan-Robinson
Respecting the ocean is a huge part of being a responsible diver, as is the understanding that we are privileged visitors to the underwater world and should conduct ourselves accordingly.
Any good Divemaster’s briefing always includes a reminder not to touch, tease or take anything from the marine environment, and the mantra “take nothing but photos, leave nothing but bubbles” is one that every diver will have heard at some point. Respecting the ocean is a huge part of being a responsible diver, as is the understanding that we are privileged visitors to the underwater world and should conduct ourselves accordingly.
Touching underwater creatures and corals can not only harm them; doing so can harm us too. There are many animals in the ocean that can cause injury if alarmed, disturbed or aggravated, some of which we know about, and many more that we do not. From innocuous looking stinging hydroids to the beautiful but venomous lionfish, from shells equipped with deadly poison to all manner of stonefish, scorpionfish, sea snakes, urchins and jellyfish, marine inhabitants are better admired from a distance suitable for your health as well as theirs. Contact with the reef itself can cause nasty wounds; many of us know from firsthand experience how long coral cuts take to heal, and how disproportionately painful even the slightest graze can be. The majority of shark bites among divers occur as a result of inappropriate behavior or reckless contact on the part of the diver. As divers, we are ambassadors for the ocean and all the creatures that live there. Particularly where threatened species like sharks are concerned, our ability to interact with them without incident is key in changing public perception of them and consequently promoting their conservation. If we follow the no-touching, -teasing or -taking rule, we can easily avoid most injuries caused by marine life. As divers, we have the potential to do great good in the underwater world. Through our explorations, we raise awareness about the marine environment and the necessity to conserve it for future generations. Divers tend to be among the most committed and conscientious promoters for ocean preservation — it’s our dive sites that we’re fighting to protect. By refraining from touching the creatures and plants that make up that world, we ensure that our impact continues to be a positive one.
The Fish That Goes Fishing
Courtesy of Wakatobi Dive Resort
When you think of a predator, what attributes come to mind? Streamlined speed, explosive agility, aggressive strength… and then there’s the frogfish. Slow, reclusive and lacking in both offensive and defensive weaponry—not to mention being far from streamlined—the frogfish wouldn’t seem to have the tools needed to become a lethal predator. Yet despite some seeming shortcomings in the attack department, these enigmatic little creatures have developed a unique strategy to capture prey: they hide in plain sight and go fishing. Truly, frogfish are one of nature’s most unusual creatures. The frogfish’s fishing rod is actually a modified dorsal fin with a fleshy appendage at its end, which serves as bait. To attract a meal, it flicks the bait up and down, just like a fisherman working a lure. If a potential target did manage to dart in and steal the bait, the frogfish is able to grow a new appendage to replace what was bitten off. To bring its prey closer, the frogfish uses camouflage and blends into its surroundings. That’s why you’ll have to look very closely among the sponges and corals on the reef to find a frogfish; they often look more like a sponge or a chunk of rock than a fish. Their coloration varies from species to species, and within the same species, while an individual frogfish is able to change its skin color and pattern to better match its surroundings. Skin textures can range from velvety-smooth to algae-covered warts, and even spots that match those of their habitat.
If a frogfish were to change its hiding spot, it could alter its coloration to hatch the new surroundings. But this doesn’t happen often, as these lurkers don’t move around much. Instead, they like to park themselves in concealment and wait for a meal to come their way. When they do move, they are as likely to walk as to swim. Frogfish often use their pectoral and pelvic fins to push themselves along the sea bottom. Of course, they can swim reasonably well when the need arises, and can also pump water out their gill openings to create a sort of jet propulsion effect. The frogfish diet includes crustaceans, fish, and even other frogfish on occasion. When a potential meal gets within six to seven body lengths, the frogfish begins its fishing routine, moving its lure to mimic a swimming or drifting morsel. If the potential prey becomes interested, the frogfish may make a slow, stealthy advance, or it may just lie in wait while working the lure. Once the victim is lured within striking range, the frogfish attacks. But this is no lighting-fast pounce—though it does take places in less than 100th of a second. Rather than move in on the prey, the frogfish literally sucks dinner into its mouth by opening its jaw with near instantaneous speed. This rapid expansion enlarges the mouth to more than ten times its resting size, creating a powerful suction that pulls the meal in. Super-sizing the bite also allows the frogfish to gobble up catches nearly as large as themselves, and its stomach can also expand to accommodate big meals. Their bizarre appearances, unique colorations and unusual hunting tactics make frogfish prized by photographers and fish watchers alike. It takes a sharp eye to spot one amid the colors and patterns of the reef, but because they tend to stay in one place, it’s often possible to return to the same spot and find the same frogfish working the same favorite fishing hole. Truly, frogfish are one of nature’s most unusual creatures.
Five Frogfish Facts
Credits to PADI
Frogfish are masters of disguise. Spot one during a dive and you will win the admiration of every diver in your group – especially photographers. Frogfish, a type of anglerfish, have a textured exterior that aids in their camouflage. While they do not have scales, their amazing ability to camouflage themselves serves as protection from predators. Frogfish vary in color and often have unique spines or bumps that change with their surroundings.
Here are some more interesting frogfish facts:
1. Unlike many animals that use camouflage as a defense from predators, frogfish mostly use their abilities to attract prey.
2. Frogfish have a modified dorsal fin that has a retractable lure resembling a shrimp, which is used to attract their prey. If their lure is eaten or damaged it can be regenerated.
3. Frogfish are carnivores. They eat fish, crustaceans and even other frogfish.
4. A frogfish’s mouth can expand to 12 times its resting size. This allows it to catch all sorts of prey.
5. Because frogfish lack a swim bladder, they use their modified pectoral fins to walk, or even gallop, across the seafloor.
There are many fish in the sea that use camouflage, but the frogfish is a real treat to see. Frogfish can be found in tropical and subtropical oceans and seas off the coasts of Africa, Asia, Australia and North America. Next time you take a dive in one of these regions take a closer look at the reef.
Have any frogfish spotting tips? Post them as a comment below…