When studying the life sciences, there are a lot of in-depth concepts to take in. Depending on the the type of science you are studying, biology vs. evolution, for example, you may even have to learn a handful of mathematical formulas to fully appreciate the material. Here, we are just having a light-hearted overview of the life sciences, so a light serving of sativa will do just fine. In my experience, sativa helps me to not get lost in wordy texts (reading that is not broken up by graphics/tables or formulas) and keep my mind sharp and able to take in all relevant information. Grinding about 60mg (less than 1/4 of a 1g bud) of sativa and smoking just a small pinch of that for over a 3-5hr period is perfect for maintaining a healthy attention span for learning. Black Flower Science Co. does not claim to be a medical professional and does not offer recommendations as a substitute for medical advice. All advice and recommendations are based on personal experience of the benefits of medical marijuana. If you are experiencing severe or declining mental health symptoms, please seek the advice of a medical professional.
Now that you’ve read the first installment of this series, you know the basics of evolution and how various taxonomic groups came into being. Let’s dive further into the discussion of taxonomic groups starting with my favorite, my beloved, Kingdom Animalia.
Introduction to Kingdom Animalia
There are 3 Domains into which all living organisms can be categorized: Archaea, Bacteria and Eukarya. Class Mammalia, home to us human beings and the mammalian wildlife we love so much, belong to Domain Eukarya. But there are so many branches in the tree of life that lead to mammals… what in those branches makes the mammals so unique, and how do we get there?
Let’s start the navigation from the first two domains: Archaea and Bacteria are prokaryotes – single-celled organisms which include bacteria such as Escheria coli (E. coli) and flagellates like Salmonella enterica (Salmonella).
Then there’s Eukarya – eukaryotes, multicellular organisms which have nuclei, and organelles, functioning parts within the cells, such as mitochondria. This is where you and I, and all familiar terrestrial, avian and marine/aquatic wildlife belong.
Domain Eukarya can be divided further into 4 Kingdoms: Protista, Fungi, Plantae, and Animalia. Protists are predominantly unicellular organisms, such as slime molds and algae. These microbial organisms make up the majority of Earth’s biomass today. (It’s kind of crazy to think about, right?)
There are more microscopic, parasitic – or free-living – species in the world than there are humans, birds, snakes, dogs, cats, fish, whales, etc. combined? Check out this BBC article, Which life form dominates Earth? to learn some jaw-dropping details on the species “numbers game” throughout the existing kingdoms.) Kingdom Fungi is made up of both uni- and multicellular organisms which have cell walls, but their cells don’t organize into larger functioning organs like our bodily tissues.
Fungi are heterotrophic, meaning they cannot produce their own food material, but must consume it from external carbon sources. This kingdom includes organisms such as mushrooms and yeast.
Kingdom Plantae consists of multicellular organisms, whose cells – which have cell walls – can organize into tissues. These organisms are both heterotrophic and autotrophic, meaning they have the ability to produce their own food materials using processes like photosynthesis. These are such organisms as mosses, flowers, trees, and much more.
And finally, our beloved Kingdom Animalia. What sets us apart?
Well, for starters, all of its members are multicellular, and those cells, which, again, are able to organize into tissues, lack cell walls. These organisms are all heterotrophic, needing to find sustenance outside of their own internal environments. Organ systems – nervous, skeletal, muscular, digestive, respiratory, circulatory, excretory, reproductive, lymphatic and endocrine – are also a characteristic of this group.
The first fossils belonging to Kingdom Animalia have been dated back to the Cambrian Period – a time of increased concentrations of oxygen, which allowed for the development of aerobic metabolism, and a mass extinction, leaving endless niche space for new species. The radiation of new species in this time is known as the “Cambrian explosion:” anaerobic metabolisms allowed for heightened energy efficiency, as energy production now had a richer source of O2 conversion, and competition had been lowered with all the new real estate (newly available niche space).
Some of the most popular examples of these first fossils come from the Burgess Shale: particularly a collection of organisms from Phylum Arthropoda: Trilobita (trilobites), Uniramia (insects such as milli- and centipedes, beetles, butterflies, etc.), Crustacea (crustaceans) and Chelicerata (arachnids such as scorpions, spiders, mites and ticks).
(My guess is you’ve come across a representation of the Burgess Shale at some point in your lifetime, specifically an image of the trilobite. Especially if you’ve got a biologist friend – this and Darwin’s “tree of life” are quite popular tattoo designs.)
There are 36 total phyla in Kingdom Animalia, but the “true animals” belong to Subkingdom Eumetazoa. This is in contrast to Subkingdom Parazoa, which consists of Phylum Porifera (sponges) who are equipped with special cells called choanocytes for influencing the water current around them, but are immobile.
Eumetazoans undergo a process in embryonic development known as “gastrulation,” which results in 2 or 3 germ layers, making the organism either diplo- or triploblastic. These three germ layers are called the endoderm, mesoderm and ectoderm.
From the endoderm comes the gastrointenstinal (GI) tract, respiratory tract, thyroid and parathyroid glands, pancreas, and more. Connective tissue, cartilage, bone, striated and smooth muscles, blood vessels, kidneys, gonads are all derived from the mesoderm. The ectoderm becomes the central nervous system (CNS), the peripheral nervous system, epidermis, and more.
So far this still includes Cnidaria and Cnetophora (jellyfish, box jellies, corals, anemones, hydra and comb jellies), Platyhelminthes (flatworms), Mollusca (snails, slugs, oysters, clams, octopi, squids), Annelida (segmented worms), Nematoda (roundworms, hookworms, pinworms, etc.), Arthropoda (spiders, scorpions, crabs, barnacles, beetles, flies, etc.), Echinoderms (starfish), and Chordata (think of your favorite animal… it’s probably a chordate). This still leaves quite a few distinctions to be made.
Well, what else sets the mammals apart?
After Subkingdom Eumetazoa comes Bilateria. Animals within this group are characterized by bilateral symmetry and cephalization (distinction of a head region on the body). This group is the contrast to Radiata, which, you guessed it, are animals which are radially symmetrical (Cnidarians and Cnetophorans). So out go the jellies – sorry guys, you can’t sit with us bilaterally symmetrical creatures.
Okay, so bilateral symmetry – is that it? Not even close.
Then the kingdom is further separated into Deuterostomia and Protostomia. These groups are meticulously differentiated by the sequence of embryonic development. Protostomes develop a mouth first, whereas Deuterostomes develop their anus first (which leads to the ever-popular saying that, excuse my language, we were all a**holes first… Sorry, I had to.)
That gives us a little bit more to work with! Now we can kick out all the creepy-crawlies – the Platyhelminthes, Mollusca, Annelida, Nematoda and Arthopoda, which, themselves, can be even further divided into groups based on whether they have an internal skeleton (Lophotrocazoa) or an exoskeleton (Ecdysazoa). But we’re not talking about them.
That leaves us with the Echinoderms (sea stars) and Chordata (dogs, cats, rabbits, etc.). How does one divide these groups?
I’d say it has a little something to do with a backbone of sorts…
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