Are you ready to learn how snowflakes form? Whether you’re teaching at home or in the classroom, studying the formation of snowflakes with your students is a fun winter learning activity. In this post, we’ll follow the journey of a snowflake as it forms high in the atmosphere and then falls to Earth! Snow is frozen precipitation; snowflakes are made of ice crystals – water in the solid phase.
Since every snowflake takes a slightly different path to the ground, each snowflake runs into unique conditions along the way (temperatures, wind currents). These different experiences impact the way each snowflake forms. Because of this, every snowflake looks different! However, each snowflake has six sides because of the properties of water molecules.
If you live in a place that receives snow in the winter, studying snow and snowflakes can be a fun activity to do with your class or homeschool. If you’re an educator planning a lesson, be sure to check out my snowflake lesson materials that go along with this blog post. You can also read my post about how to measure snow as a hands-on classroom activity for learning about snow and the water cycle!
Now, let’s see how a snowflake forms, in six steps…
One
The formation of a snowflake begins with a dust particle high in the earth’s atmosphere with temperatures below freezing.
Two
Water vapor from the air is attracted to the dust particle.
Three
As water from the air freezes around the dust particle, it begins forming a six-sided prism.
Four
As more water from the air freezes on the snowflake’s surfaces, branches may form on each of the six sides.
Five
As the snowflake becomes larger, additional branching may develop off each main branch.
Six
If temperatures at ground level are below freezing, the frozen snowflake will reach the ground.
Learn about snow with Wild Earth Lab:
Are you putting together a snow lesson plan for your science classroom or homeschool? Be sure to check out my snow learning materials! I have options for various grade levels, and best of all you’ll save time planning your lesson while supporting my blog with your purchase!
The beach is a wonderful place for bird watching, especially if you’re visiting from far away and used to a landlocked setting. A trip to the ocean opens up a world of unique bird species thriving in their natural habitat. Here, you’ll encounter a fascinating array of seabirds and shorebirds—each adapted to life in a saltwater environment.
Despite the common habitat that they share, the birds of the ocean are very diverse – you’ll see a huge array of beaks, wing shapes, and foot types. Through adaptation, these species have each carved out their own place in the coastal ecosystem, making the ocean an exciting destination for any bird enthusiast.
For teachers and parents: If you are learning about seabirds and shorebirds with kids, whether you’re a parent or an educator, I highly recommend checking out my sea & shorebirds unit (coastal birds) and my waterbirds unit (freshwater birds). These printable sets include everything you need to learn about bird life cycles, adaptations, and bird ID. These two units are also found in my Bird Bundle. Plus, the materials feature my watercolor bird artwork, as seen in this post.
Seabirds and shorebirds are both seen at the beach, but there are some differences between them. Shorebirds, also called “waders” in some regions, are birds found along the coast. Shorebirds all fall within the biological order Charadriiformes. This order includes sandpipers and plovers, among others. Many shorebirds have long legs perfect for wading through shallow water, walking, or running. Many feed along the water’s edge or by probing their bills in shallow water or sand. Unlike seabirds, not all shorebirds can swim particularly well.
On the other hand, “Seabird” is a blanket term for the many bird species that are adapted to living in a marine environment. Seabirds are excellent swimmers. They use their webbed feet to paddle while floating atop the water. Some even dive beneath the surface and swim to great depths to hunt food. While graceful in water, many seabirds move with considerably more difficulty while on land. Some spend months at a time in the open ocean and only come to land to nest along coasts, lay eggs, and raise their young, often in large groups called colonies.
Shorebirds in the surf. Photo by Blair Damson on Pexels.com
Types of Shorebirds
Here are some shorebirds you might spot at the beach or coast:
Sandpipers
These birds get their name for the unusual way they feed – probing their bills in the sand for buried goodies like crustaceans and insect larvae. Sandpipers are quite diverse. Within this group, there are many shapes and lengths of bills. This variety allows different species to probe for food at different depths.
For example, the long-billed curlew can extract food from deep in the mud, with its impressively long downward-curved bill! Other examples of sandpipers include yellowlegs, turnstones, and sanderlings. A widespread and diverse group, sandpipers are one bird family you’re likely to spot on your next trip to the beach!
A long-billed curlew probing in the sand
Plovers
If you see a small bird running along the water’s edge, there’s a good chance it’s a plover! Plovers are a diverse group of small shorebirds with long, thin legs. They are quick on their feet, which helps them scamper along the beach as they forage for food on the ground. Any time I see one of these tiny birds at the beach, I find myself worrying that the next wave might just sweep it away – but they always seem to run to safety just in time!
You can tell plovers apart from other shorebirds because they have relatively short necks and bills. Plumage varies between plover species. Examples of plovers include killdeer, golden plovers, and semipalmated plovers.
Semipalmated plover
Stilts and Avocets
You may see these leggy birds probing and scything for food in shallow waters of coastal wetlands with their long, thin bills. To tell the difference between a stilt and an avocet, just look at the bill. Stilts have straight bills while avocets’ bills curve upwards. Both have long necks and long, thin legs.
American avocet
Oystercatchers
These unique shorebirds are most easily recognized by their large, bright-red bills. Their bills are special tools for opening shells to get to the food inside. They also have long, pinkish legs and black and white plumage.
American oystercatcher
Types of Seabirds
Here are some seabirds you might spot at the beach, coast, or in boats on the open ocean.
Gulls & Terns
Gulls and terns are likely some of the most common birds you’ll see at the beach. They come in a variety of sizes and colors, and are opportunistic feeders. They can catch (or find) food in a variety of different ways. Unfortunately, these adaptable birds often end up feeding on human garbage, which can make them (and other wildlife) ill. For this reason, it’s important to always pick up your trash while visiting the shore!
Terns look quite similar to gulls, but usually are smaller with a more streamlined body. Terns are fast fliers, and some make incredible migrations, such as the Arctic tern, which journeys from the Arctic to the Antarctic and back each year. Talk about a long flight!
Herring gull
Skimmers
These distinctive birds are related to gulls and terns, but are of special interest because of the unusual way they catch their food. Skimmers feed by “skimming” the water’s surface with their distinctive bills. They fly low to the water with an open beak, letting the lower beak drag through the water. When the beak touches a fish, it snaps shut like a mousetrap. Pretty cool!
A black skimmer skimming the surface of the water for food
Pelicans
Pelicans are another common bird at the beach. They are most easily identified by their large size and a pouch for holding prey spanning from the lower part of the bill to the throat. If you are lucky, you can watch pelicans hunt while you sit on the beach. They put on a spectacular show, diving from the air into the water to catch fish.
Brown pelican
Cormorants
Cormorants are some of the strangest-looking seabirds, in my opinion. With a long hooked bill, long neck, and fully webbed feet, a cormorant is well-equipped to swim underwater hunting fish like some sort of bizarre sea creature.
While graceful in water, these oddities appear awkward on land, standing with a nearly upright posture since their flippered feet are attached near the rear of their body. Furthermore, cormorants often stand around gawkily holding their wings partially open to dry in the sun since they do not make water-resistant oils for their feathers. If you are lucky enough to spot one of these majestic misfits, feel free to stare!
Double-crested cormorant
Puffins & Auks
If you visit a coast in far-northern regions at the right time of year, you may see puffins! Puffins, and their relatives like murres and guillemots, are sometimes collectively called “auks”. While they may remind us of penguins with their round bodies and black and white plumage, auks are actually more closely related to seagulls. Similar to penguins, auks are excellent divers that pursue fish by using their wings to “fly” underwater. However, auks like puffins can also fly in the air too!
Atlantic puffin
Gannets & Boobies
These birds are absolute diving machines! They are amazingly adapted for one thing – plummeting headfirst from the air into the water! Gannets and boobies have sturdy, pointed bills and streamlined bodies that help them hit the water at high speeds without hurting themselves. They use the momentum of the dive to swim underwater and catch a meal. This special form of hunting is known as “plunge diving”. If you wish to see gannets and boobies hunting, you may want to get on a boat, as these seabirds thrive in an open-ocean environment.
A northern gannet plunge diving for fish
Albatrosses & Tubenoses
Albatrosses and their relatives (petrels, shearwaters, and storm-petrels) make up the bird order known as Procellariiformes, also sometimes called “tube-nosed seabirds” or “tubenoses”. Your best bet at seeing one of these stunning seabirds might be on a boat, as they spend significant portions of the year hunting in the open ocean.
Albatrosses’ claim to fame is their impressive wingspan. Albatrosses have what is known as active soaring wings – which are extra-long and slender wings that act like a glider plane. These wings help them harness sea breezes to fly and migrate without using up too much energy flapping. The wandering albatross has the largest wingspan of any bird – nearly 12 feet!
Black-footed albatross
Penguins
While you are unlikely to see one at the beach (unless you live in Antarctica or other select locations in the Southern Hemisphere), penguins are technically a type of seabird. Like other seabirds, they spend significant time living and hunting in the open ocean. Many penguins are uniquely adapted for life in extremely cold and icy places.
Chinstrap penguin
Other Waterbirds at the Beach
Ducks, swans, and egrets are all waterbirds. Photo by Robert So on Pexels.com
Sea and shorebirds are not the only birds that live in water. “Waterbird” is a general term for any bird that spends significant time swimming or wading in water. This can be in saltwater or freshwater. All seabirds and shorebirds are also waterbirds, but not all waterbirds are sea or shorebirds. Other waterbirds include geese, ducks, herons, coots, grebes, and many more.
Furthermore, sea and shorebirds are not the only birds found at the seaside. Waterbirds like herons and loons live in freshwater and saltwater habitats, but are not specifically considered seabirds or shorebirds.
Study Seabirds and Shorebirds with Wild Earth Lab:
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Rocks and minerals are an important topic in the field of geology. Learning about rocks and minerals can be so fun for both kids and adults. Here are 7 hands-on rocks and minerals activity ideas to try out in your classroom or homeschool.
A note for teachers:if you’re planning to teach rocks & minerals, great learning resources are key to deepening understanding. That’s why I created my complete Rocks & Minerals Unit. It’s packed with hands-on lab activities, thoughtfully crafted visuals, and all the worksheets and handouts you need to study rocks and minerals. Plus, every purchase helps support this blog! ❤️
Try making a model of the rock cycle. This is a popular rock and mineral activity for the classroom! There are many ways to do this – with chocolate, marshmallows, Starburst candies, crayons – the list goes on.
The basic concept is this:
Sedimentary Rocks: big solid chunks lightly compacted until they stick together. This can be done by cutting up the material into pieces and then squeezing the pieces together in your hands until they stick together.
Metamorphic Rocks: warped under heat and/or pressure, but not enough to fully melt. This is done by briefly warming your material to a moderate temperature in an oven and then applying pressure.
Igneous Rocks: fully melted, the re-solidified material. This can be done by fully melting your material in an oven and then allowing it to cool at room temperature.
You can use chocolate to model the rock cycle! Melted chocolate symbolizes molten rock! Photo by Monstera Production on Pexels.com
This activity is great for teaching the basics of the rock cycle before continuing on with the other rocks and minerals activity ideas.
2. Mineral Lab
Minerals are the building blocks of rocks. Geologists can examine minerals for their physical properties and then identify them. A minerals lab is super fun because it involves testing minerals for magnetism, acid reaction, and other unique physical properties! To test for these properties, you will need to make or buy a mineral test kit, such as this test kit (external link).
With a little practice, you and your students can identify common minerals too. Read my separate post here about how to set up your own minerals lab in your classroom. You can also download my Minerals Mini Study, which includes all of the worksheets, handouts, and directions that you’ll need for an awesome mineral lab in your classroom!
The activities in the blog post come from my Minerals Mini Study. Download the mini study with worksheets, handouts, directions, and more.
3. Guided Geology Hike
Are there any national parks or state parks in your area? Some have rangers who will put on guided nature hikes covering many topics, including local geology.
If not, you could also reach out to a local geology expert to join your class or homeschool group on a hike to learn about geology. When I was a graduate student, a homeschool group reached out to me to lead a geology hike like this. We hiked a short way through a canyon and talked about how plate tectonics and flowing water helped shape the area.
4. Make Rock Candy
This is a tasty way to learn about mineral precipitates, which you may know form some of our sedimentary rocks, such as limestone. This activity takes several days, during which you will watch crystals form! You can follow a rock candy recipe, such as this recipe (external link).
5. Rock Identification
Rock IDcan be challenging, but it is so rewarding to be able to identify common rocks in your area. Learn about foliation, grain size, rock compositions, textures, and more! If you are looking for a good place to get started with Rock ID, I think you’ll love my Rocks Mini Study. It includes all the printable handouts, worksheets, and directions you will need for an awesome Rocks Lab! Another fun activity to try is Rock ID Bingo – more on this below!
If you are looking to learn how to identify rocks, try out my Rocks Mini Study. It includes all the handouts, worksheets, and directions for a rock ID activity!
6. Play Rock or Mineral Bingo
These are great review games for practicing rock and mineral identification. Each student gets a bingo card with different rocks or minerals. The teacher then reads out the properties of a mystery rock or mineral. The students must figure out which rock or mineral it is, then mark it on the bingo card!
I’ve created these mineral bingo and rock bingo sets (complete with calling cards!) to help you play this game in your classroom:
7. DIY Fossils
Unlike living things, which come and go, rocks stick around for incredibly long periods. This allows rocks to act as time capsules, preserving clues about our planet’s past – fossils! Learn about how fossils form by creating your own fossils (external link).
Bonus: see real fossils up close for inspiration! Look for a geology museum in your area to see collections of amazing and rare gems, minerals, rocks, fossils, and much more! You can also look for gem and mineral show events in your area (external link).
Many of the rock and mineral activity ideas from this post are found in or go great with my complete Rocks and Minerals Unit! It is a complete set of printable materials including worksheets, handouts, classroom posters, lab activities, and much more!
Reptiles are a cool group of critters – and not just because they are cold-blooded! In this post, you will read about the different types of reptiles: snakes, lizards, turtles, tuataras, and crocodilians. Each of these groups has its own unique characteristics but also has several key traits shared with all reptiles.
A note for teachers: Are you an educator planning a reptiles lesson? I think you’ll love myReptiles Unit, which can also be found within my even more comprehensive Vertebrates Bundle. The information and some of the artwork in this post come from the reptile unit. The unit also includes hands-on activities, thoughtfully crafted diagrams and visuals, handouts, worksheets, and everything you need to teach reptiles–plus you will support this blog with your purchase! 💚
Reptiles are part of a bigger category of animals called vertebrates, which means they all have a backbone. There are seven different groups, or classes, of vertebrates on Earth. These include amphibians, birds, mammals, reptiles, and three kinds of fish.
These are the main classes of vertebrates.
Reptiles are not always the easiest group to define. There is a lot of diversity within this group. From legless snakes to shelled turtles and armored crocodiles, the reptile group has some incredible creatures. Unlike other classes of vertebrates, scientists now know that the group we call reptiles is not an isolated evolutionary lineage. This means that some members of the reptile group are not quite as closely related as we once thought they were.
What counts as a reptile?
Some reptiles might seem very different from one another, but all types of reptiles share a few special traits. You can use these traits to help you identify reptiles:
A backbone
Breathe air with at least 1 functional lung
Scales or scutes
Ectothermic
From the cute gecko to the venomous rattlesnake, and everything in between, there are so many unique creatures to discover in the world of reptiles! The main types of reptiles covered in this post are: lizards & snakes, tuataras, turtles, and crocodilians.
Some species of lizards can drop their own tails when they feel threatened. This is a great defense because a predator will be distracted by the tail while the lizard escapes. The tail later regrows.
Snakes have nostrils for breathing but smell using their tongues.
There are about 600 venomous snake species in the world, but only a few poisonous snake species.
Examples:
Cobra, python, rattlesnake, boa, garter snake
3. Tuatara
Drawing of a tuatara – by Wild Earth Lab.
Order:
Rhynchocephalia
Key traits:
Four limbs
Long tails
Spiny back
No ear holes
Scales
Fun Facts:
The tuatara is only found in New Zealand. Despite its lizard-like looks, the tuatara is not a lizard. Lizards and snakes are in the order Squamata, but the tuatara belongs in its own order, Rhynchocephalia. All animals in this order except for the tuatara are extinct today.
4. Turtles
Sea turtle illustration by Wild Earth Lab.
Order:
Testudines
Key traits:
Four limbs
Short tail
Bony shell with scutes
No ear holes
Scales
Fun Facts:
Turtles and tortoises can live to be very old. The Galapagos giant tortoise can live for over 150 years. Even small turtles can live for decades. Many people do not realize a pet turtle can be a lifelong responsibility!
Crocodilians are some of the closest living relatives of the dinosaurs.
The saltwater crocodile, the largest crocodilian, can reach a length of over 20 feet (6 meters)!
Examples:
Alligator, crocodile, caiman
Study Reptiles in Your Classroom:
Are you teaching about reptiles in your classroom or homeschool? There’s no need to scramble to create the perfect set of materials for a reptile unit – I’ve already done it for you! You and your students will love studying reptiles with my complete Reptiles Unit!
Camouflage is an adaptation that helps an animal disguise its appearance. There are many types of camouflage. Camouflage may help an animal blend into its background or look like something inedible or toxic.
Many prey animals use camouflage to protect themselves from predators. Also, some predators use certain forms of camouflage to help them hide and sneak up on prey.
Are you an educator planning to teach camouflage in your classroom? You may enjoy trying out this simple camouflage lab activity – read about the lab activity and download my printable worksheets and directions for it:
Types of camouflage include concealing coloration, disruptive coloration, countershading, disguise, and mimicry. Here are a few forms of camouflage:
1. Concealing Coloration
Concealing coloration is when an animal’s colors match its background to help it blend in. Often, animals with concealing coloration are shades of green, gray, and brown so that they do not stand out against leaves, twigs, rocks, and soils. In the polar regions, animals may have white fur so that they blend in with snow.
Examples: A huge number of insects, lizards, turtles, snakes, rodents, and other prey animals have concealing coloration. Some animals, like chameleons, can even change the color of their skin to match their background more closely. Arctic animals with concealing coloration to blend in with snow include some arctic foxes, polar bears, ptarmigans, snowy owls, and arctic hares.
2. Disruptive Coloration
Disruptive coloration includes patterns like spots and stripes that make it difficult to see the outline of an animal. These patterns of contrasting colors can visually break up an animal into pieces. It is difficult to hunt an animal if you cannot tell where its body begins and ends!
Examples: zebra, leopard
3. Countershading
Countershading is a common type of camouflage for aquatic animals. Their bellies are light-colored, like the surface of the water when viewed from below. Their backs are dark, like the water’s depths when seen from above.
Examples: sea turtles, dolphins, sharks
4. Disguise
Disguise is when an animal looks like something inedible. For example, it disguises itself as a rock or stick. Predators do not realize that the animal is something good to eat.
Animals use mimicry to trick predators into thinking they are something yucky, dangerous, or inedible. The mimic may be a relatively harmless animal that looks similar to a dangerous animal. This clever disguise fools predators into thinking the harmless animal is far more dangerous than it is.
Examples: milk snakes look like venomous coral snakes. Viceroy butterflies look like poisonous monarch butterflies.
A non-toxic viceroy butterfly (left)mimics a poisonous monarch butterfly (right).
A Different Strategy: aposematism, aka warning coloration
Aposematism is not camouflage – in fact, it is the opposite of camouflage! Aposematism means warning coloration. Venomous, poisonous, and otherwise dangerous animals often have bold patterns and colors. Contrasting patterns or stripes of red, orange, yellow, black, and white let predators know to back off! Gila monsters and coral snakes are two venomous reptiles with warning coloration. A skunk’s black and white stripes are another example of warning coloration.
A coral snake and a Gila monster are two venomous reptiles with the striking warning coloration known as aposematism.
You will also find the camouflage lab materials in my complete Reptile Unit! From Gila monsters to chameleons, the world of reptiles is full of some crazy patterns and disguises! If you enjoyed learning about the types of camouflage in this post, I know you will love learning more about the camouflage and coloration of reptiles in my complete Reptiles Unit!
As you know, the Earth is orbiting the Sun, and the Moon is orbiting the Earth. Every once and a while, the Sun, Moon, and Earth all line up and something very special happens. A solar eclipsehappens when the Moon passes between the Earth and the Sun. During a solar eclipse, the Moon totally or partially blocks out the Sun during the daytime. There are three main types of eclipses: total solar eclipse, annular solar eclipses, and partial solar eclipses.
There are a few different types of solar eclipses. The most dramatic type of eclipse is a total eclipse. A total eclipse happens when the Moon passes directly between the Earth and the Sun and blocks the Sun from our view on the ground. Totality is the phase of the eclipse when the Moon fully covers the Sun. When this happens, part of the Earth is totally in the moon’s shadow. If you are in the shadow, it becomes dark during the daytime. The Sun’s corona is seen behind the Moon during totality.
Annular Eclipse
The second type is an annular eclipse. During both annular and total solar eclipses, the Moon passes directly between the Earth and the Sun. However, in an annular eclipse, the moon cannot fully cover the sun because the moon is at its furthest distance from Earth on its elliptical orbit.
Partial Eclipse
The third type of solar eclipse is a partial eclipse. Partial eclipses are the most common. During a partial eclipse, the Moon passes between the Earth and the Sun, but is not perfectly lined up. Consequently, the Moon only blocks part of the Sun.
Life’s beginning varies a lot among mammals. We can group mammals into three main categories based on how their babies come into the world. The main types of mammals are called monotremes, marsupials, and placentals.
A Note For Teachers: If you’re an educator planning to teach types of mammals, great learning resources are key to deepening understanding! I think you and your students will love my complete Mammals Unit, which you can also find within my huge Vertebrates Bundle (plus you’ll support my blog with your purchase! ❤️ )
The echidna (left) and platypus (right) are monotremes.
Most mammals give birth to live babies instead of laying eggs. However, there are a couple of exceptions: platypuses and echidnas. They belong to a special group called monotremes. Even though they are unusual, monotremes, like the platypus, still provide milk for their young after they hatch. Monotremes are found in Australia and surrounding islands.
Marsupials
Kangaroo (left), koala (middle), and the extinct thylacine (right) are all marsupials.
Marsupials are another interesting type of mammal. They have a very short gestation period – that is the amount of time they are inside their mom’s belly. When they are born, they are very tiny and need a lot of care. They crawl into a pouch or open area on their mother’s belly, where they stay warm, safe, and can drink milk while they grow. A famous example of this is a kangaroo with a joey in its pouch. The kangaroo, like most marsupials, lives in Australia. South America is also home to many marsupials, and there is even one marsupial in North America: the opossum.
Placentals
Placental mammals are a large group, including deer (left), bats (middle), and prairie dogs (right), as well as many others.
The largest group of mammals is called placentals. They give birth to live babies after a longer gestation period. A special organ called the placenta helps give these mammals the nutrients they need while still in the womb. Placental mammals are born more developed than marsupial babies. Some, like baby deer (called fawns), can even stand up and start walking the same day they are born. Placentals are found in many habitats all around the world.
Learn about mammals with Wild Earth Lab
Check out my Mammals Unit! Learn about monotremes, marsupials, placental mammals, and much more!
If you enjoyed learning about the types of mammals in this post, I know you will love using my other earth and environmental science materials in your classroom!
Ferner, K., Schultz, J. A., & Zeller, U. (2017). Comparative anatomy of neonates of the three major mammalian groups (monotremes, marsupials, placentals) and implications for the ancestral mammalian neonate morphotype. Journal of anatomy, 231(6), 798-822. Available via Wiley Online Library: https://onlinelibrary.wiley.com/doi/10.1111/joa.12689
A keystone species is an organism that plays an exceptionally large role in its ecosystem. It provides materials or services that enrich the lives of other organisms in the ecosystem. Without the keystone species, the ecosystem would look very different and other organisms that rely on the keystone species would suffer. Now, let’s look at a few examples of keystone species!
Beavers in Wetlands
A common example of a keystone species is a beaver in a wetland. Beavers build dams on streams, causing water to back up and form ponds and wetlands. The result is a much more complex ecosystem with a greater variety of habitats.
A beaver wetland can support a very diverse plant and animal community. Beaver ponds provide a place for other animals to live and forage. A beaver wetland is a great habitat for wetland plants that like to grow in standing water. Without the beaver, the wetland ecosystem slowly degrades.
Saguaro Cactus in the Sonoran Desert
Like the beaver, the saguaro cactus is a keystone species. In the Sonoran Desert ecosystem, the saguaro plays a central role providing shelter and food for many other species.
Birds like elf owls, hawks, and woodpeckers live in cavities within the saguaro’s trunk. The saguaro’s flesh helps keep these homes temperature regulated so their occupants stay cool during hot desert days.
The saguaro flower provides nectar that feeds desert pollinators, like bats, doves, and bees. Once pollinated, the saguaro makes large fruits that are also a vital food source for desert animals. Coyotes, tortoises, birds, and others eat the fruit and disperse the saguaro’s seeds in their scat.
Many desert animals have a type of symbiotic relationship with saguaros known as mutualism. This means both the animal and the saguaro benefit from the relationship.
Prairie dogs are keystone species in grasslands and prairies because of their tunnels. They are exceptional excavators that build large networks of underground tunnels. These tunnels actually help keep the soil healthy. Digging tills and aerates the soil, and prairie dog scat provides a fertilizer for prairie plants.
Additionally, when prairie dogs abandon burrows, other prairie animal species can move in and use these homes. Not all animals are as good at digging as prairie dogs, so they rely on abandoned prairie dog homes for shelter. Finally, prairie dogs are a food source for grassland predators like coyotes and hawks.
Wolves in Forests
Although scarce today, wolves are a natural keystone species in many types of forests. Wolves help keep the populations of deer, elk, and other undulates under control through hunting them. Amazingly, this impacts the plant community of the forest! Let me explain: deer and elk are voracious plant eaters. When deer and elk numbers grow unnaturally high, plants struggle to grow fast enough to keep up with the hungry undulates. But when wolves are around, the deer and elk populations stay in check, and the plants benefit.
Even a few wolves can really make an impact. These is because the presence of wolves changes the behaviors of deer and elk, scaring them into more protected parts of a habitat. When there are no wolves around, deer and elk will more freely browse in any part of the habitat, including open areas like meadows and riparian zones.
Explore curriculum from Wild Earth Lab:
If you enjoyed this post, I know you will love using my environmental science materials in your classroom!
Fortin, D., Beyer, H. L., Boyce, M. S., Smith, D. W., Duchesne, T., & Mao, J. S. (2005). Wolves influence elk movements: behavior shapes a trophic cascade in Yellowstone National Park. Ecology, 86(5), 1320-1330.
Kotliar, N. B., Baker, B. W., Whicker, A. D., & Plumb, G. (1999). A critical review of assumptions about the prairie dog as a keystone species. Environmental management, 24, 177-192.
Some saguaro cacti live for 200 years or longer! Saguaro cacti grow very slowly. The speed of growth depends on many factors such as precipitation, temperature, and soil quality. Let’s explore the saguaro cactus life cycle in five steps! Notice that desert animals play a key role in two of these steps.
For Teachers and Parents: If you’re an educator planning to teach kids about cactiin your classroom or at home, great activities and visuals are key to deepening understanding! I think you and your students will love my complete Cactus Unit(plus you’ll support my blog with your purchase! ❤️)
A seed germinates. The two cotyledons open to form a tiny plant. Seeds that germinate in shady areas such as beneath palo verde trees are most likely to survive through the fragile young stages and reach maturity.
The seedling cactus grows through its first summer and develops more areoles and spines. At just a few millimeters in height, the seedling is so small that it can be difficult to spot.
2. Maturity
It may take ~35 years for a saguaro cactus to reach maturity and produce its first flowers.
The rate of growth depends on environmental conditions such as precipitation, temperature, soil quality, and the type of cactus. For saguaro cacti, growth happens very slowly over many years.
When a cactus reaches reproductive maturity, it can produce its own flowers. Time to reach maturity depends on the cactus species. For example, the saguaro cactus takes several decades to reach maturity.
The lesser long-nosed bat is a nighttime pollinator of the saguaro cactus
The cactus flowers bloom. Cactus flowers make tasty nectar to attract pollinators like bats, bees, and doves. Pollen is transferred between plants by the pollinators. This is a type of symbiotic relationship called mutualism because both the pollinator and the plant benefit. The pollinator gets a tasty meal of nectar, and the plant gets pollinated.
4. Fruiting
Saguaro fruits are a food source for many animals in the Sonoran desert. People sometimes eat the fruit too.
Once pollinated, the cactus fruit begins forming from the ovary of the flower. Cacti can produce huge amounts of fruit. For example, a single saguaro cactus may produce upwards of 100 fruits each year. That’s a lot of fruit! The ripened fruit splits open, revealing sweet flesh and seeds. This sends the signal to animals that the fruit is ready to eat!
5. Seed Dispersal
When an animal eats the saguaro fruit, it ingests some seeds. The seeds are then dispersed in the animal’s scat.
Desert animals like birds, coyotes, and tortoises eat cactus fruit and disperse seeds in their scat. This is another example of a mutualistic relationship between an animal and a cactus. The animal gets a meal of fruit, and the cactus gets its seeds dispersed. If the cactus is lucky, some of its seeds will be deposited in locations with good growing conditions. Over its lifespan, a single saguaro may produce millions of seeds. However, only a few of those seeds will germinate, grow, and reach maturity.
Helmy, Olga. 2021. Carnegiea gigantea, saguaro. In: Fire Effects Information System, (Online). U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Missoula Fire Sciences Laboratory (Producer). Available: www.fs.usda.gov/database/feis/plants/cactus/cargig/all.html
There are many types of cacti, which are found in dry places and deserts. Cacti are succulent plants. Succulent plants are thick and fleshy for storing water. While all cacti are succulents, not all succulents are cacti. Cacti are unique because they have areoles – cushion-like bumps that cover the outside of a cactus. One or more sharp, pointy spines are attached to each areole. Spines are a type of modified leaf. Most cacti species have no true leaves. They do, however, produce flowers and fruit, which provide an important food source to desert animals.
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Cacti are a diverse group. There are more than one thousand different species of cacti. Some look like a single rounded shape (like a barrel cactus). Others have complex, branching arms or pads (like a prickly pear). They can be as tiny as a grape or grow taller than a house.
Without further ado, let’s explore some of the types and groups of cacti in the United States:
Saguaro Cactus
The saguaro is the largest cactus in the U.S., with some of the older individuals reaching heights of 40-50 feet or more! While it is probably the best-known cactus in the United States, the mighty saguaro actually has a fairly small range and is native to the Sonoran Desert only. The saguaro is actually a keystone species of the Sonoran Desert. Cavities in the large trunks of these tree-sized, columnar cacti provide homes to animals. Their flower nectar and fruit are also food for many Sonoran desert animals. The saguaro cactus is a single species (Carnegiea gigantea).
Photo by Nicole Ashley Rahayu Densmoor on Pexels.com
Organ Pipe Cactus
A relative of the saguaro, the organ pipe cactus (Stenocereusthurberi) boasts an impressive size. This large columnar species can reach 10 feet or taller! You can identify an organ pipe cactus by its many stems branching out from a single point at its base. Organ pipe cacti are found in the Sonoran Desert, especially in Organ Pipe Cactus National Monument in Arizona. This cactus thrives in the heat and is quite sensitive to freezing temperatures.
Prickly Pears
Prickly pears are a group of cacti within the genus Opuntia. You can identify prickly pears by their branching, flattened pads. These pads are not leaves. But they do perform photosynthesis, like leaves. If identified and prepared properly, the pads can be a delicious food. The fruits of prickly pears are also eaten by both animals and humans. You will find prickly pears in many deserts. Some species of prickly pears grow outside of deserts too.
Chollas are a group of cacti within the genus Cylindropuntia . They are closely related to prickly pears and have a similar branching appearance, but their stems are cylindrical, not flattened. There are many species of chollas, such as the buckhorn cholla and the teddy-bear cholla (pictured). While some chollas look soft and cuddly from a distance, they are, in fact, covered in very sharp spines!
Hedgehog Cacti
Hedgehog cacti belong in the genus Echinocereus. They grow in clusters and are quite small, usually under a foot tall. They have ribbed stems and a rounded shape with no branching. Hedgehog cacti are beloved for their beautiful and brightly colored flowers. You can see hedgehog cacti in deserts and dry regions across the southwest United States and Mexico.
Barrel Cacti
Barrel cacti belong in two different cactus genera: Ferocactus and Echinocactus. They are named for their rounded, barrel-like shape. Species vary dramatically in size, with some barrels under a foot and others over 10 feet tall! They are found throughout the southwest United States and parts of Mexico.
Pincushion Cacti
Pincushion cacti belong in the genus Mammillaria. Types of cacti in this genus are also sometimes called nipple cacti. Pincushion cacti are characterized by hooked spines and a very small size. Often, they are just a few inches tall. There are many species of pincushion cacti. You will find pincushions across Central America and Mexico. A handful of pincushion species have ranges extending into the southwest United States.
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