This is the time of the year when we begin seeing amphibian eggs show up in most of the bodies of water in West Hylebos Park. Last Saturday, a gentleman asked me how long it took for an amphibian egg to hatch and it occurred to me that I hadn't written about the life-cycle of a frog in about two years. This seemed like a good time to rectify that matter. Amphibians are some of the most fascinating creatures that you'll ever run across. Mammals have fur, birds have feathers, fish have scales, snails have shells, but amphibians have nothing but skin. Unlike some other creatures, amphibian skin is neither tough, leathery, or scaly. As a matter of fact, it's very thin and fragile. That's why amphibians need to live in dark damp places like a bog.
Frogs begin life in the water as eggs. Unlike chicken eggs, amphibian eggs have no shell. Instead, they're encased in a jelly-like substance that's held together by surface tension. Every amphibian has it's own favorite place to lay it's eggs and the eggs of each species look different from those of other species. Some are larger and some are smaller. They differ slightly in color. Most amphibians in the West Hylebos Wetland attach their eggs to some kind of branch, twig, or stick that they find in the water. Depending on the species, the eggs can be laid singly, in small groups, or in large floating mats. They can be above the surface of the water, resting directly below the surface, or suspended deeper in the water. The best places to look for amphibian eggs are in tree-wells, or areas where the water is moving slowly, but isn't stagnant. Amphibians like to lay their eggs in Marlake, which is a man-made lake that's dependent on rain water, but don't usually lay their eggs in Brooklake, which is a natural lake fed by an underground aquifer.
Six to twenty-one days after the eggs are deposited in the water, tadpoles emerge from the eggs and start swimming around. Tadpoles are aquatic. They have gills and breathe in the water like fish. Most tadpoles are vegetarians, but they won't remain so as adults. There are a lot of creatures in the wetland who like to eat tadpoles, so tadpoles are very shy. Tadpoles who want to live long enough to become frogs hang out in shallow areas that have a lot of vegetation, so they can quickly dash away and hide when they detect danger. Bullfrog tadpoles will actually jump out of the water and squeak when then detect danger, then quickly head for deeper water where they can hide. This behavior has startled a great many visitors who aren't familiar with it. I've had to assure them that this isn't Lake Placid. We have no man-eaters lurking in the depths of Marlake. This is usually about the time in my talk where children request crocodiles and alligators. Sorry, kids, those critters require a different climate for their survival. They wouldn't be able to make their home in Marlake.
During the twelve to sixteen weeks following their emergence from the eggs, tadpoles begin to change. Their tails are slowly absorbed by their bodies as they begin to grow arms and legs. When this metamorphosis is complete, the baby frogs crawl out onto land. At Marlake, the frogs usually do this en masse. One day, the water is full of tiny frogs; the next day the grass along the edge of the lake is hopping with hundreds of tiny baby frogs. Anywhere from a day, to a week or two after that, the frogs will leave the grass, once again en masse, and hop into the nearby bushes. By this time, their gills have disappeared and they've beome air-breathing creatures. This is about the same time that they also stop being vegetarians. Frogs have long-sticky tongues with which to grab their food. They'll eat just about anything they can fit into their mouths, including other frogs. Yep, frogs are cannibals! Unlike some creatures, frogs also tend to be lazy. They don't run around chasing after their food like coyotes and wolves, or pounce on it from the air like hawks. That expends way to much energy as far as a frog is concerned. Instead, frogs prefer to find a nice cozy place to sit and wait for their food to come to them; then, when an unwary insect strays too close, the frogs long sticky tongues zap out like a flash, stick to the insects, and drag them into their mouths. A few less insects. Many happy frogs.
Some frogs, such as the red-legged frog, like to live next to a pond or small body of water. Sometimes, I'll find four or five of them hanging out along the edge of a single tree-well. I'll see them sitting there, make a complete circuit of the boardwalk, and find them still sitting in exactly the same spots some twenty minutes later. They're like little frog statues. They sit there and don't move a muscle for what seems like hours at a time, conserving energy. But, startle them and watch what happens! I was watching three of them one day when a family with children came by and frightened them. Each of the three frogs chose a different course of action. One immediately jumped into the water and hid under a branch, just peeking the tip of it's nose and eyes out far enough to see what was going on. One immediately jmped up onto the bark of a tree and tried to blend in with the moss. That little frog went from ground level to my eye level in two quick jumps. The third frog chose to freeze right where he was, possibly thinking that if he didn't move, he wouldn't attract attention. No, wait, ... that's what he was doing in the first place! Like I said, frogs are pretty lazy.
Others, like pacific tree frogs and striped chorus frogs, prefer to live on or around trees in the bog. Most of the very loud frog songs we hear around Federal Way in the spring are being generated by tree frogs or chorus frogs. The males have a bladder beneath their chins that they can blow up into a big echo chamber.
When it gets cold, frogs like to dig deep within the mud, or under brush, and sleep through the winter. All of their body processes slow way down, just like a bear. In spring, the frogs wake up and breeding begins. Once again, the frogs return to the water to lay their eggs and the great circle of life begins all over again.
Remember how I said that frogs will eat nearly anything they can fit into their mouths? Well, frogs not only eat insects, like mosquitoes, that might bother us, but they are also a vital source of food for many of the other creatures who live in the bog. Greeat-blue herons, snakes, and owls all love to eat frogs.
Because frogs have no shells, fur, or scales, and spend a lot of their lives in or near water, they're extremely sensitive to chemicals that wash into our rivers, streams, and lakes. If we want to have frogs around for other generations to enjoy, we must be mindful of what we allow to enter our water. We must also be careful about properly disposing of our trash, such as this cigarette butt that was carelessly tossed into a tree-well in the park. If you pack it in - please pack it out! We all need to take care or frogs could be lost forever!
Invasive species, such as this bullfrog, are also of concern in the park. Bullfrogs do not belong here. Rumor has it that they were imported to Washington State to be used as a food source in restaurants and escaped. Since then, they have moved from lake to lake throughout the state, consuming all of the native frogs, salamanders, and snakes. They appeared at Marlake about four years ago and have made themselves at home there. Since then, we've watched the native frog population visibly decrease. If it's not native to the park, please resist the urge to add it to the park's population.
Frogs can differ substantially in size, color, and markings within the same species, making amateur identification very difficult. Even if we aren't completely sure which species we're looking at, we can still have a lot of fun looking for them and watching their behavior. We have red-legged frogs, pacific tree frogs, striped chorus frogs, and bullfrogs living within West Hylebos Park. How many can you find? Where are they living? What are they doing? Feel free to drop me a comment and let me know about your finds. I'd love to hear from you!
Teri I. Lenfest
