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How do you divide the eukaryotes? September 19 2019, 0 Comments
If I asked you how you would divide the eukaryotes into groups, what would you say? Many people would say protists, fungi, animals, and plants. This is the idea presented in Five (or Six) Kingdoms classification. There is a more enlightening way to divide the eukaryotes, one that students currently see in introductory college courses.
The DNA revolution and the development of systematics rather than plain classification have given us a new view. Systematics includes the relationships between taxonomic categories instead of listing them with no information about their shared ancestors. It is a young science that has produced many changes and will likely produce many more.
This is not to say that we don’t have useable information right now. The largest categories of eukaryotes have been defined, and they are called the eukaryotic supergroups. There are four of them presently, and so the eukaryotes can be divided into four groups. Here’s an introduction to the archaeplastida, SAR, excavata, and unikonts aka Amorphea.
Archaeplastida is the lineage that acquired the first chloroplast. Its name means “ancient plastids.” A plastid is a type of organelle in a eukaryotic cell, and the category includes the chloroplast, whose name means “green body.” The archaeplastida lineage includes red algae and green algae, along with the embryophytes or land plants, which evolved from a green alga. This lineage is the only one that incorporated an ancient cyanobacterium into its cells. The origin of the chloroplasts in other lineages is a more complicated story.
The SAR lineage is named for the three main branches within it, stramenopiles, alveolates, and rhizarians. These lineages were defined independently and then researchers gathered enough evidence to conclude that they share a common ancestor. The stramenopiles (aka chromists or heterokonts) include brown algae, golden algae, diatoms, and water molds. Alveolates include dinoflagellates, apicomplexans (parasites such as malaria), and ciliates. The rhizarians include foraminiferans and radiolarians, single cell organisms that build amazing outer shells called tests.
And where did these branches of life get their chloroplasts? It seems that chloroplasts are NOT easy to acquire. Apparently, it is easier to take one from another cell than to acquire one by eating a cyanobacterium. An ancestor of the stramenopiles and alveolates probably ate a red alga and kept its chloroplasts. Euglenas, which we meet below, got their chloroplasts from a green alga.
The third eukaryotic supergroup is the excavata, also called the excavates, but I see potential for confusion between the word as a noun vs. a verb. The lineage is named for a groove that looks like it has been excavated from the cells of some members. The excavata include the euglenas, which are free-living, and the trypanosomes, which are parasites. Other members of this group include the parasite Giardia and organisms that live in the guts of termites and help them break down cellulose. These have reduced mitochondria, so small that they were first described as lacking mitochondria.
I know you have been waiting for the last of the four supergroups, our own lineage, the unikonts (“single flagellum”) also known as the Amorphea (“having no form”). “Wait a minute,” you may be thinking, “we definitely have form.” The amoebas that belong to this lineage do not, however. The Amoebozoa lineage includes most of the slime molds or social amoebas as well as the single cell ones. Some of the latter build hard coverings (tests) for themselves. The other members of the unikonts are the fungus kingdom and the animal kingdom, which are sister kingdoms, having shared a common ancestor right before they branched off. There are other single cell organisms that are related to animals and fungi as well.
As you can see, the old protist kingdom had many different lineages of life shoe-horned into it, and the kingdoms that developed from its members were chopped off and boxed separately from it in the Five (or Six) Kingdoms scheme.
Why should you or your children learn about the supergroups of eukaryotes? It gives you a richer view of life and one that your children will see in their future studies. Will the names stay the same? Maybe, or maybe not, but these are the names in current college biology books, and it is worthwhile to learn about them and their members now.
Enjoy your explorations of the living world!
Priscilla
What impressions of plants are we giving? Part 3. Stems and leaves August 12 2019, 0 Comments
When we use the botany impressionistic charts to introduce children to plants, are we giving them correct information and the important ideas for them to know? That is the question I’ve been asking in this series. I’d like to call the charts “An overview of how plants work” or perhaps “Imagine how plants work." In English, the term “impressionistic” can imply that the material is hazy and unclear.
Several of these charts show people doing things to illustrate what the plant accomplishes. For instance, little men are shown anchoring roots like tent stakes. While some of this may help children understand plants, I find the real plant characteristics and real plant structures wonderful and inspiring as they are.
What do the traditional charts say about stems? One chart says that some stems are weak, and so they have to grow some structure to help them climb to reach the sunlight. This one has always driven me nuts. Nature doesn’t make weak organisms; natural selection acts against the poorly adapted. There is a better way to look at stems that climb. They have adaptations that allow them to grow upwards but don’t require them to develop a thick, rigid stem. Some kinds of vines have flexible woody stems. They are called lianas and they include grape vines and cat’s brier (Smilax). Lianas are common in tropical forests, and their stems certainly shouldn’t be called weak, as the photo shows.
The chart on stems that climb could also show children that plants do many things with their stems beyond the usual connecting roots and leaves. Stem adaptations include food storage (kohlrabi, potato) and water storage (cacti, other succulents). Two quite different looking specialized stems help grow new plants. Corms are short, thick stems that store food and propagate the plant (gladiolus, banana). Without corms, we wouldn’t have bananas to eat because the domestic bananas are seedless. Runners are greatly elongated stems that enable the plant spread its offspring across the ground (strawberries). Thorns are short, pointed stems that discourage herbivores (hawthorn). Climbing roots, twining petioles, twining stems, and tendrils represent many ways that plants can fulfill their need to reach the sunlight.
The traditional botany charts include a depiction of photosynthesis in the leaf. Please make sure that you are giving children accurate ideas about photosynthesis. Hint: If your “chemical factory in the leaf” chart shows carbon monoxide being formed, it is giving false information. Why should we ask children to imagine false ideas when we can give them steps in the real process? The process of photosynthesis has quite a lot of details, and it must be greatly simplified for children, but if we are going to give them an idea of what goes on, it should be a valid framework to which they can add details later.
The “chemical factory in the leaf” should show that sunlight is used to break apart water molecules. It is the chlorophyll molecules that capture the Sun’s energy. The sunshine-requiring “light reactions” produce hydrogen ions and oxygen molecules. (They also produce high energy electrons and energy-rich molecules (ATP), but that is more chemistry than beginners need.) The hydrogen is joined to a carrier molecule, moved to a different area, and combined with small, carbon-containing molecules that have had a carbon dioxide attached. A series of reactions produces sugar. Most charts simply show the hydrogen and carbon dioxide entering a structure of some sort and sugar coming out. That is likely to be enough information for the beginner.
Check the depiction of carbon dioxide on your charts. It is a linear molecule. There is a carbon in the center with an oxygen on either side. The oxygens are directly opposite one another – 180 degrees apart. It isn’t like water, which is v-shaped.
I’ve seen charts that show the sugars from photosynthesis being combined into starch, which does happen in plants. A little bit of starch is made in the chloroplast, and it acts as fuel during the nighttime. Starch, however, is NOT transported through the plant’s phloem. Starch is too big to go into solution. The transportable product of photosynthesis is the sugar sucrose (table sugar). The sucrose travels to leaves, stems, and roots, where it is converted to starch, which stores the chemical energy until it is needed. Sucrose is made from two 6-carbon sugars, so there is some processing of the product of photosynthesis before it is transported.
And then there is the chart that shows leaves worshiping the Sun. Do we worship the food on our plates? No, although a healthy serving of appreciation for the food that sustains us is a good thing. The real leaf story is so much more interesting. We can help children imagine how a plant positions its leaves and appreciate beautiful leaf arrangements. As for the leaves, they are arranging themselves to get maximum sun but minimum damage. Sunlight comes with heat, and leaves take action to avoid getting cooked. A leaf in the shade may be oriented horizontally. In full sunlight, the same species may turn its leaves on edge to protect them from heat. In deserts, many plants orient their leaves to catch less of the Sun’s hot rays.
I’ve always found much in nature that is inspiring and remarkable, and that’s without turning plants into people. When we learn about a natural phenomenon, there always seems to be more of the story. This alone can be inspiring to children. We can let them know that there is much more to the story of plants and how they work than we show on the botany charts.
What impressions of plants are we giving? Part 2. Roots do more than we think. July 14 2019, 0 Comments
Last time, I wrote about the Montessori material called “Botany Impressionistic Charts.” I’ve looked at the meaning of the work “impressionistic,” and the only definition that seems to be relevant to the charts is “overview.” If I ever produce a version of this material, I will call it “An Overview of How Plants Work.”
In my previous article, I addressed the needs of plants, including the one so often omitted, the need for oxygen. This time, I’m looking at roots. Well, not literally looking at them other than on the weeds I’ve been pulling, but I’m reading about them.
Roots on the traditional charts are rather simple. They anchor the plant in the soil, take in water, and prevent soil erosion. This makes them seem about as interesting as tent stakes and drinking straws. There is a lot more to roots. I recently acquired a book called The Nature of Plants: an introduction to how plants work. The author, Craig N. Huegel, states “Roots may well be the most important plant organ and the least understood.”
Roots are a last frontier for botany for good reason. They are hidden in the ground, and any attempt to see them disturbs them. In the past few years, there have been attempts to image root growth with MRI, CAT scans, and optical scanners in a tube that is buried in the ground amid the roots. Botanists are realizing that understanding roots is very important, both for the health of the plant and the planet. The ability of a plant to take up carbon dioxide depends on its roots.
There are some items of misinformation on the traditional “Botany Impressionistic Charts.”
- Roots grow only to the drip line of the foliage. Wrong! If you have ever weeded a garden or dug up plants, you’ll know this one is a myth. At least in all but the most mature trees, the feeder roots extend about 2-3 times the diameter of the canopy according to Morton Arboretum, Colorado State University Extension, and other reliable sources. The root spread of herbaceous plants varies tremendously depending on species and environment, but I have seen many root maps of herbaceous plants that show roots extending well beyond the diameter of the foliage.
- As a result of the spread of roots, the leaves of the plant do not direct rainwater within the dripline because the roots end there. In fact, I found only one example of leaves sending rainwater to roots, and that was desert rhubarb from Israel.
- Roots seek water. This happens, but not like it is usually illustrated. Most of a tree’s roots grow in the top 6-24 inches (15-60 cm) of the soil. These laterals are the primary water absorbers. There aren’t many larger deep roots, and these don’t turn and head off to distant water. Hydrotropism occurs over millimeter distances, not meters. The part of the root that turns is the root cap, which means only the tip end of the root changes course. Botanists describe root foraging, in which roots grow out from the plant all directions and give rise to many small branches when they encounter pockets of water or minerals that they need. This would be a better picture to give children.
Useful concepts illustrated on the charts include:
- Roots hold the soil. This is certainly an important function of roots. Another chart could go beyond this and show that roots improve the soil as well. They make channels in the soil and excrete substances that cause soil particles to clump. This helps water and oxygen penetrate the soil. They also excrete substances that help the plant solubilize and gather nutrients such as phosphorus and iron. These exudates feed the helpful soil bacteria near the roots as well.
- Roots grow around obstacles. They seem to feel their way around the obstacle until their path is open.
Here are other important ideas about roots that are not illustrated on most sets of botany impressionistic charts.
- The first root of young plants grows down and the shoot grows up (gravitropism). (Soon after the primary root forms, the lateral roots grow from it. In most monocots, the primary root is short-lived, and many adventitious roots grow from the base of the stem.)
- Roots store the extra food that the leaves make. This is easy to see in a root like a carrot or beet, but even slender roots store food.
- Roots have feeding partnerships with fungi (mycorrhizae) and bacteria. These microbial partners also help defend the root from harmful microorganisms. The majority of plants relies on mycorrhizae and grows poorly or not at all without them. Children need to know about this, the most wide-spread symbiosis on Earth.
- Roots can be adapted to serve other functions. Examples include prop roots, climbing roots, parasitic roots (haustoria), and pneumatophores.
I encourage you to give children an accurate, exciting view of roots. There is plenty of mystery and discoveries to be made about the root system. Here is another book that can help you, How Plants Work: The science behind the amazing things plant do by Linda Chalker-Scott.
Happy botany studies!
Priscilla
What impressions of plants are we giving? Part 1. The needs of the plant. June 12 2019, 2 Comments
I have been looking at these charts and asking myself what else children today need to know about plants, and whether everything shown on the original charts is still considered valid.Moving past zoology and botany April 30 2019, 0 Comments
Normally, I write about elementary or secondary education in my blog. In this one, I’m addressing an issue that starts in early childhood, and it affects the way children view the living world in their later studies.
Traditionally, Montessori life science (biology) was divided into zoology and botany. The divide began when young children sorted pictures into animals vs. plants. This exercise fit well with the two kingdom approach to classifying the living world. I certainly hope that Montessori teachers no longer use two kingdoms. Biologists began moving away from two kingdoms in the mid-1800s, although it took a hundred years and major advances in biochemistry and microscopy to complete the break. We can give children a more useful overview of the living world than simply animals and plants.
It is time to quit thinking of life science as zoology or botany, or structuring our teaching albums (manuals) this way. When we offer only two categories for living things, children miss much of the living world. While young children are not ready for lots of details, they can sort pictures of living things into three categories, the third being “Other living things.” This tells them that there are organisms that are neither plants nor animals, and it keeps the door open for further learning. Mushrooms, lichens, and kelp are examples of macroscopic organisms that fit under the “Other” heading.
I started my work to bring current science concepts and content to teachers over 20 years ago. My first conference workshop was about the Five Kingdom classification. I spent nearly a decade helping teachers move from two kingdoms to five kingdoms. Then I had to switch gears again as expanding knowledge (via DNA and RNA) of the relationships between living things led to new concepts of classification, principally the Tree of Life and phylogenetics. My book, Kingdoms of Life Connected: A Teacher’s Guide to the Tree of Life, has learning activities and resources for exploring all the branches of life and viruses, too.
The microscopic living world is more abstract and harder to observe than plants and animals, but that does not mean that children shouldn’t know about it. They can learn that microorganisms help plants grow, recycle nutrients, and make foods like yogurt and cheese possible. The disease-causing microorganisms are the ones that we experience most directly, and these get the most attention, but children need to understand the vital importance of microorganisms to all ecosystems.
The book, Tiny Creatures, by Nicola Davies and Emily Sutton (2014) is a valuable resource for introducing young children to the microscopic world. These authors have a second book (2017), Many: The Diversity of Life on Earth, which supports a more inclusive view of life. The Invisible ABCs by Rodney P. Anderson (2006) sounds like it would be for early childhood, but it looks better for beginning elementary. This publication from the American Society for Microbiology has accurate information and good images of the organisms. Its breezy style makes this abstract world more interesting.
Moving past botany and zoology also means considering more than biological classification. It means thinking about the ecosystems, environments, and interactions of life, the structures of life, and the evolutionary history of organisms. Elementary children will have a better idea of the importance of microorganisms after they read Ocean Sunlight: How Tiny Plants Feed the Seas by Molly Bang and Penny Chisholm (2012). This book uses the term “plants” for the ocean’s protists that perform photosynthesis, even though many are not on the green algae-plant lineage. More importantly, it shows children the microbial underpinnings of the ocean ecosystem.
In elementary life science studies, there will be times to focus on the animals or the plants, but children will have a better perspective if they start with an introduction to the whole Tree of Life and learn to use this conceptual framework. As children develop their abstract thinking, they are likely to be interested in exploring all the branches of life. They will need good tools, such as magnifiers and microscopes, to help them observe the protists and prokaryotes. They also need appropriate search terms for finding resources they can read and understand.
I hope you and your children enjoy studying the greater living world.
Priscilla
A chemistry chart that IS NOT the periodic table February 13 2019, 0 Comments
We all know and use the periodic table. This icon of chemistry classrooms has many versions. The chemistry community is celebrating the table’s 150th anniversary this year. You can see the latest version of it here: https://iupac.org/what-we-do/periodic-table-of-elements/ . If you would like to know more of its history, see https://www.sciencenews.org/article/periodic-table-history-chemical-elements-150-anniversary.
All elementary and higher classrooms need to have this chart. I recommend that you start with a simple version that has the elements’ symbol, name, and atomic number but little else. That’s enough information for beginners. The color scheme should make it easy to tell the metals, metalloids, and the nonmetals apart. Samples of some common and safe elements will help children see the significance of this chart.
My card set, “Discovering the Periodic Table”, helps children find out why the elements are arranged as they are on the periodic table. You can see more about at https://big-picture-science.myshopify.com/collections/physical-science/products/discovering-the-periodic-table.
I like to tell children that if they meet an alien from another planet, they could communicate via the periodic table because the chemical elements are present throughout the universe. We can tell this by the unique wavelengths of light that each element gives off.
After children are familiar with a simple periodic table, they may find a chart that illustrates the elements attractive. These charts vary in quality, and most are confusingly busy. Make sure that an illustrated chart shows something that is meaningful to children or that it shows the actual element. Vague scenes or unfamiliar objects are not likely to help children grasp the concept of elements.
There is another chart for chemistry that is very useful for advanced elementary and middle school levels. It is the classification of matter chart. If you search the Internet for “classification of matter chart,” you will find many flow charts. Big Picture Science offers the chart from InPrint for Children, which I helped design. This chart shows the chemical forms that matter can take. First, it divides matter into pure substances and mixtures. It has four photo cards with information on the back for each of four categories – elements, chemical compounds (both are pure substances), and homogeneous and heterogeneous mixtures.
This chart has information that children need to imagine the kinds of atoms or molecules that may be in a substance. They see how chemical elements are a part of all matter and how elements combine in compounds. Most matter that they encounter is some sort of mixture. The chart will help them sort out the major types of mixtures as well.
The photos show four common elements that you can have as samples in the classroom – zinc, copper, sulfur, and silicon. The latter is available from scientific supplies as the lump form, laboratory grade. Be sure to get the lump or crystalline form. This element is also sold in a powder form, but this doesn’t allow children to see the shiny crystals.
Enjoy exploring the chemical elements and ordering them on the periodic table and the classification of matter chart!
Priscilla
What goes on a plant kingdom chart? December 27 2018, 0 Comments
Like its counterpart, the animal kingdom chart, all Montessori elementary classrooms need a plant kingdom chart. A current version of this chart will have the same elements as a traditional one, but the groups will not have the same labels or arrangement as they have had in decades past. DNA studies and phylogenetic systematics have changed the look of the plant kingdom, and our charts need to reflect this. It is hard to find a solid consensus among botanists on the “right” names, but that is no excuse for giving names that we know are obsolete.
I’ve listed my recommendations for contents of a current plant kingdom chart below. The names that I think are most important are in boldface type. The other names may also be useful. Ask yourself, “Will elementary children be able to use this name to find information that they can read and understand?” If you do a search using the name, do you find information that you can use and understand? If not, consider dropping the more technical name and using the common name for the lineage, the one I emphasize below. The terms on charts for children should be useful for understanding the diversity of life AND for finding further information.
Plant Kingdom (land plants, embryophytes)
Bryophytes (nonvascular plants)
Liverworts (Phylum Marchantiophyta)
Mosses (Phylum Bryophyta)
Hornworts (Phylum Anthoceratophyta)
Vascular Plants or Tracheophytes
Lycophytes or club mosses and relatives (Phylum Lycophyta)
Euphyllophytes, the “true-leaf” plants
Fern clade or Monilophytes (Class Polypodiopsida)
Whisk ferns and relatives
Equisetums or horsetails
Ferns or leptosporangiate ferns or true ferns
Seed plants or Spermatophytes
Gymnosperms
Cycads (Phylum Cycadophyta)
Ginkgo (Phylum Ginkgophyta)
Gnetophytes (Phylum Gnetophyta)
Conifers (Phylum Pinophyta)
Angiosperms or flowering plants (Phylum Magnoliophyta)
Basal angiosperms
Magnoliids
Monocots
Eudicots
For a beginner’s chart, I start the plant kingdom with the land plants, the embryophytes. It is acceptable to add the green algae because they are closely related to embryophytes, but it is clearer if children learn about land plants first, and then add their relatives. Advanced students are ready for a chart of the Viridiplantae (green plants), which includes the green algae lineages and the land plants. It is important for children to understand that land plants and green algae share a common ancestor.
Don’t feel bad about leaving off phylum/division names. While the animal kingdom phyla have been rearranged by DNA studies, they have kept their names. Plant kingdom phyla or divisions, whichever you wish to call them, aren’t as useful anymore. In fact, I have a widely-used, advanced textbook for plant systematics that uses no phylum/division names at all. Instead, it simply uses names with no ranks for the major lineages, such as lycophytes, euphyllophytes, seed plants, and angiosperms. It still uses orders, families, genera, and species, the Linnaean ranks that botanists continue to use for plants.
There has been a big change that centers on the ferns. An older scheme had four phyla, Psilophyta, Lycophyta, Sphenophyta, and Pterophyta or Pteridophyta. These groups, often called “ferns and fern allies,” were considered more or less equal, but now we know that the lycophytes are a separate lineage from the other three. The fern clade, now considered by some to be a phylum, has three groups once considered separate phyla – the whisk ferns, horsetails, and the true ferns.
I see no reason to put notably out-of-date information on a plant kingdom chart. I especially encourage you to remove any images that are no longer considered plants. If you still have a mushroom on your plant kingdom chart, children are going to associate fungi with plants, even if you tell them that we know now that fungi are closely related to the animal kingdom and not at all close to plants. The visual impression that a chart gives to children is powerful, and it is important to get it as close to current as we can.
Change seems to come slowly in the general knowledge of plant systematics. I did an Internet search for plant kingdom charts and classification, and I found an amazing range of information from very old to current. Some websites even use the terms “cryptogams” and “phanerogams,” which came into use about 1860. Botanists haven’t used them in academic publications for at least 40 years. It is not that they are “wrong,” but they describe a superficial view that botanists had over a century ago. Our knowledge has grown, and there are better ways of expressing the differences among plant groups.
The flowering plants are currently divided into several lineages. I listed the main ones above, basal angiosperms, magnoliids, monocots, and eudicots. Botanists no longer use only the monocot and dicot subgroups, although these are still common in field guides and older publications. The flowering plants make up about 90% of the plant kingdom, and their orders have been defined in the last two or three decades using DNA studies. They deserve their own chart of orders and families.
My plant kingdom chart from my Tree of Life shows the lineages and their relationships. The plant kingdom chart from InPrint for Children gives children more practice with the categories.
Here are some quick ways to check the information on a plant kingdom chart for your classroom. If the chart shows a row of evenly spaced boxes, it isn’t giving children all the information they need. Bryophytes need to be grouped together and somehow spaced apart from the tracheophytes. Lycophytes should be separated from other spore-producing plants. If the club mosses, whisk ferns, true ferns, and horsetails are all grouped together and perhaps called “fern allies” or “pteridophytes,” that’s obsolete. There should be something to show that the club mosses are a different lineage from the three branches of the fern clade, and if possible, that ferns are more closely related to seed plants. If the term “dicots” or “dicotyledons” appears instead of “eudicots,” then that needs to change. Eudicots (“true dicots”) are the old dicots minus the magnoliids and the basal lineages such as water lilies.
The same criteria for illustrations on a kingdom chart apply to animals and plants. Can you see the important structural features that enable children to recognize the lineage? For example, can you see a fern’s fiddleheads or its sori? Can you see the sporophytes of the bryophyte lineages? Sporophytes need to be visible and described in the text. The reproductive structures and foliage of the gymnosperms help children tell the difference between those lineages. Flower illustrations should clearly show stamens and pistils. Consider showing a fruit as well because fruits are unique to the flowering plants.
In the text for the chart, give children a range of examples whenever this is possible. Children, like much of our society, are less likely to be familiar with plants than they are with animals. They may be surprised to learn that grasses, maples, and oak trees are flowering plants.
Enjoy opening children’s eyes to the diversity of plants! For more information about the plant kingdom and its members, see my book, Kingdoms of Life Connected.
What goes on a chart of the animal kingdom? November 29 2018, 0 Comments
A chart of the animal kingdom is standard equipment for any Montessori elementary classroom. The chart could be purchased or made by the guiding adult. Either can be appropriate and useful to children. Conversely, either can have significant mistakes and misconceptions. Here are guidelines for choosing or making an animal kingdom chart.
First of all, the animal kingdom chart presents the major phyla. “What are those phyla?” you may ask. There are about 35 phyla of animals, and that is far too many to present to elementary children. Some have few members, and children are not likely to ever experience their members. The Wikipedia article on animals has a table that gives the number of species in the 11 largest phyla. Here is my list of phyla that show important structural features or notable evolutionary features. I consider the following “must haves” for the animal kingdom chart for beginning elementary.
Phylum Porifera, the sponges
Phylum Cnidaria, the anemones, jellyfish, corals, and hydras
Phylum Platyhelminthes, the flatworms
Phylum Annelida, the segmented worms – earthworms, leeches, and polychaete worms
Phylum Mollusca, the mollusks – snails, clams, octopuses, etc.
Phylum Nematoda, the nematodes or roundworms
Phylum Arthropoda, the arthropods – insects, crustaceans, spiders, and many others
Phylum Echinodermata, the echinoderms – starfish, sea urchins, sea cucumbers, etc.
Phylum Chordata, the chordates – lancelets, tunicates, and vertebrates (NOTE: Chordata is not equal to Vertebrata. The latter is a subphylum of Chordata.)
These belong on all animal kingdom charts to illustrate the range of creatures in this kingdom. There are other phyla of interest that can be added for a more advanced chart or one that spans elementary and secondary levels.
Phylum Ctenophora, the comb jellies – This phylum is significant because it is likely to be the second branch of the kingdom after the sponges. Ctenophores occur worldwide in marine waters. They were formerly grouped with the cnidarians in the obsolete phylum Coelenterata.
Phylum Rotifera, the rotifers – If children look at pond water under the microscope, it is likely that they will see these tiny animals. On a chart, rotifers would go near flatworms and segmented worms.
Phylum Ectoprocta or Bryozoa, the bryozoans or moss animals – Children are unlikely to observe these animals because they are about 0.5 mm across, but they may find bryozoan colonies at the beach. Use a guide to seashore life to identify them. Almost all bryozoans live in colonies, which can look like crusts on other organisms or rocks. Some form larger colonies that are commonly known as brown hairy tongues.
Phylum Brachiopoda, the brachiopods – These were much more common in the fossil record than they are now. The two halves of their shells enclose their top and bottom halves, whereas the two halves of a clam shell enclose the left and right sides of the mollusk’s body. This makes brachiopods a bit challenging for the beginner. I would hold this phylum for later introduction, perhaps along with studies of the Paleozoic Era.
Phylum Hemichordata – This small phylum of marine creatures includes acorn worms and pleurobranchs, which are tiny colonial animals. The extinct graptolites are placed in this phylum. Despite its name, this phylum is more closely related to echinoderms than to chordates. It is too confusing for beginners. Let children get a firm grasp of chordates before you introduce this phylum.
Other minor phyla – There is plenty for beginners to learn without adding minor phyla, however it is good to be prepared in case your children encounter an animal of a minor phylum. Many of these will be marine animals, and so a guide to marine life can be useful to place these finds into a phylum. Possibilities include ribbons worms, horsehair worms, velvet worms, and tardigrades.
Keep in mind why we are introducing children to various animal phyla. In this kingdom, each phylum has a different body plan. Children learn about the unique characteristics of each lineage. To this end, the illustrations on the chart should show at least one example that illustrates the identifying traits. Close up photos of a portion of the animal’s body or photos with a messy background or many animals together are not helpful for seeing the body plan of the organism.
Of course, the description of the phylum needs to include its scientific name. Don’t stop there, however. Children may not be able to find further information that they can read and understand unless they have common names as well. They likely know many of the common names, and it boosts learning to start with something known and move to new information.
The phylum description needs to state simply and straightforwardly the main features of that lineage. For example, segmented worms should be described as having repeated segments in their bodies. If you have a good illustration, it is easier to describe important visible features.
Finally, how do you arrange the phyla on the animal kingdom chart? HINT: It isn’t in an evenly-spaced straight line. Some phyla are more closely related than others. The animal kingdom chart that high school or college students will see is a phylogeny, a branching diagram. If you do not wish to start with a phylogeny, you can still group related phyla together. The echinoderms and the chordates are sister phyla. So are the nematodes and the arthropods. The mollusks and annelids are another closely related pair. The animal kingdom chart from InPrint for Children is a good example of grouping phyla.
For any studies of classification beneath the level of phyla, it is best to use a phylogeny. For an example, see my material, “From the Chordates to Mammals: Exploring the Tree of Life.” https://big-picture-science.myshopify.com/collections/biology/products/from-chordates-to-mammals-exploring-the-tree-of-life
Happy animal explorations! For more information about the animal phyla and the phylogeny of the animal kingdom, see my book, Kingdoms of Life Connected. 