Sand Crabs

A rite of passage for any kid on a sandy, ocean beach is digging for sand crabs. But you have to be in the right place. Wait in a spot where the waves will come in and wash gently over your feet. Then as the water washes back out, look for bubbles in the sand. When you see the bubbles, DIG! If you’re lucky, you’ll come up with a sand crab tickling the palm of your hand (it’s trying to burrow).

It turns out that area of breaking waves is called the swash zone. And this is where the sand crabs feed. They will move in and out with the tide, moving only backward (unlike other types of crabs that can move in any direction, these crabs can only move in one direction). Sand crabs use the claws on their hind legs, and their tails, to dig themselves into the sand backward. As a wave recedes, the crabs uncoil a set of antennae (they have two sets!). These antenna work like a net, filtering out microscopic plankton for them to eat.

Female sand crabs can lay up to 45,000 eggs (whoa!). She carries these eggs on her abdomen for 30 days until they hatch. After that she’s done, and the larvae drift off in ocean currents, which can distribute them far and wide. That may seem like a lot of offspring for one crab, but as both larvae and adults, they are food for many birds and fish.

One last thing – if you collect sand crabs in a bucket of sand, don’t leave them there too long. The sand and water heat up, which isn’t good for the crabs. Let the sand crabs go in the swash zone and watch them burrow into the sand backwards (in 1.5 seconds, apparently).


On my summer trip to Maine we spent all of our time on the coat, enjoying the ocean, the rocky shoreline, and the tidepools. Among the state’s many wonders, I was awed by how great the tidal ranges were there; the difference between high and low tide was on average between 8-12 feet, and even higher in the more northern parts of Maine. I grew up on the east coast, experiencing tide ranges of only 2-3 feet on the Maryland shore. Which made me wonder, why is the tidal range so much greater in some places? I reasoned, incorrectly, that the range of tide increased with latitude.

A bit of research revealed that the tidal range experienced in any one location has nothing to do with latitude or longitude, but is instead affected by several other factors. To start, tidal range is affected by the shape and geometry of a coastline. Coastlines with more curves (inlets, bays, peninsulas, etc.), such as that of Maine, will have a greater tidal swing than coastlines that are straighter and less varied.

In addition, in the northern hemisphere, the continents are closer together in the higher latitudes, thus constricting the ocean and creating higher tidal ranges – the water has to go somewhere! However, in the southern hemisphere, the continents are not as close together in the higher latitudes and therefore this region does not experience the same tidal range as their northern counterpart.

Finally, continental shelves affect the tides. In places where the continental shelf just off the coast is shallow and wide, the greater the tidal range. And conversely, in places where there is no continental shelf and the water offshore is deeper, the less tidal range there will be, as in Hawaii – something I’ve also wondered about!

For even more information about tides, watch this video with Neil deGrasse Tyson!


Footsteps in the Forest: Biome Explorers

Our last biome journey is into the world’s forests. Did you know that there are more than 60,000 different species of trees in the world? They also cover one third of Earth’s land, totaling more than three trillion trees! In Footsteps in the Forests we’ll take a walk on a rainforest canopy walkway, sit quietly to observe temperate forest wildlife, and bundle up to visit a chilly boreal forest.

First stop – the Amazon rainforest! There we’ll see an amazing variety of biodiversity in each of the four layers of the rainforest: the forest floor, the understory, the canopy, and the emergent layer. Hopefully we’ll see monkeys swinging from tree to tree, toucans tossing fruit to one another, and leafcutter ants marching one by one – HURRAH!

The next stop on the journey is a temperate forest in North America, home to both deciduous and coniferous trees. Other plants include ferns, mushrooms, mosses, and wildflowers. These forests are also home to many kinds of mammals, reptiles, amphibians, insects, and birds. As we sit and listen we may hear squirrels chittering, and woodpeckers peck, peck, pecking away.

For our last stop, in the boreal forest of Canada, grab a coat because even in the summertime, it doesn’t get very warm. Summers are also short in the boreal forest, which is why most of the trees are coniferous; since their needles don’t fall off before winter, they are able to soak up sunlight all year! Many animals here are only part-time residents, but full-time residents like snowshoe hares, lynx, and moose are well-adapted to survive in the cold and snow. Or, you could make like a bear and hibernate, sleeping away the winter!

No matter where you travel, there’s lots to see and learn, and lots of exploring to do!

Tour the Tundra: Biome Explorers

Grab a coat – on our next biome exploration we will Tour the Tundra to discover the plants and animals that inhabit the Arctic, the Antarctic, and alpine tundra. This biome is vast, treeless, and mostly frozen – it’s also the coldest of all biomes and gets roughly the same amount of precipitation as deserts. Despite this, there are amazing plants and animals that call the tundra home.

We’ll see herds of caribou and millions of birds that have migrated hundreds of miles to take advantage of the short summer in the Arctic. There are also Arctic fox and hares. These hardy animals are year-round residents who change their coats each season to camouflage themselves – white in the winter and brown in the summer. There are hardy plants there, too – over 1,700 types!

In the Antarctic there is less biodiversity, but still some plants and animals thrive. Most of the region stays covered in ice all year but look closely in the few ice-free spots and you’ll see moss and lichen; there are even two species of flowering plants in the Antarctic. Most of the animals we’ll see are just temporary summertime residents living on the coast and in the ocean, including lots of penguins!

Finally, we’ll hike up to the alpine tundra of Colorado – one of my favorite places to visit in the summer. What might we see? Marmots, pika, moose, elk, deer, bear, bighorn sheep, mountain goats, and more. We’ll also see dozens of different species of wildflowers, even in this environment with wind, cold, intense sun, and a short growing season. Remember, though, that these tundra biomes are fragile so watch where you step and stay on the trail!

Grassland Globetrotting: Biome Explorers

Book #3 in my upcoming picture book series is Grassland Globetrotting. In this book we journey across grasslands – wide open spaces of grasses, grazing animals, and frequent wildfires. They are places where there’s enough precipitation for grasses and flowers to grow, but not trees, and cover about 20% of Earth’s land area. The plants there are well adapted to this climate, with underground stems where new growth can begin and strong, deep roots that act like an anchor for the plant and can store water, energy, and sugar. The grasses also have narrow leaves so less water is lost to evaporation.

The first stop in the book is to the temperate grassland of North America’s Great Plains. Looking out across the sea of grass you might be able to see bison, pronghorn, prairie dogs, and black-footed ferrets, or a male greater prairie-chicken strut, strut, strutting his stuff trying to find a mate! The rich soil also hosts hundreds of different species of grasses and wildflowers, including milkweed which monarch butterflies depend on as they migrate.

The second half of our grassland journey takes us to a tropical savanna in Africa. This is where one of the greatest migrations on Earth occurs with over a million wildebeests, zebras, and gazelles moving across the savanna in search of water. This savanna is also home to lions, giraffes, elephants, and more.

On this journey you’ll also learn how fire is important to grasslands, and how about how the grazing and trampling of all those hooved herbivores is beneficial to the grassland plants. No spoilers here…you’ll have to read the book!