1. HOW HAS KINGDOM ANIMALIA INCREASED IN COMPLEXITY?...( See Explained Phyla page for more info if needed) The first organisms we see are the sponges, which are very basic, minus their choanocytes.
In the Cnidarians, we see the first free swimming organisms, in their medusa stage. They also go through Alternation Of Generations, and have nematocysts. They also are the first organism to exhibit radial symmetry and 2 germ layers. For reproduction, we see external fertilization, and a gastrovascular cavity for digestion (done extracellular). We also see a mouth and an anus at the same opening. For a nervous system, we see a nerve net, ocelli and statocysts, and a hydrostatic skeleton for the first time.
Once we get to the Platyhelminthes, we see a new structure called a pharynx, and cephalization to form a head. Flatworms also are the first to live on a host. We also see bilateral symmetry and three germ layers, for the first time. They also reproduce asexually by reproduction, and also reproduce sexually by INTERNAL fertilization. Their gastrovascular cavity consists of many folds, while they digest using new evolved structures called flame cells. For a nervous system, there is a new structure called ganglia, and a nerve ladder with a transverse.
In the Nematods, we see the first mouth and anus at separate locations, and because of this they have a complete digestive system. They are also the first organisms to be pseudocoelomates, which means they have a false coelom. For reproduction, Nematods have separate sexes- this is the first time we see this. They also have a true nerve cord, located on their dorsal and ventral sides.
The Annelids are where we see some big changes. First, they have segmentation with a little bit of specialization. They are also coelomates, meaning they have a true coelom. Circulation is where the magic happens, and where we see a primitive heart in the form of 5 Aortic arches. They also have two blood vessels, and a closed circulatory system. For digestion, we see a digestive system with coordination, as well as a crop and gizzard, for the first time. There are also nephridia and a bladder in order to excrete wastes. For a nervous system, Annelids have a more advanced cerebral ganglion, and a larger nerve cord with peripheral ganglion. They are also the first organisms to use gills in aquatic organisms to respirate.
The next group is the Molluscs, which have three structures we haven't seen before: the muscular foot, the visceral mass, and the mantle. For circulation, we see the first true heart, and the two options of an open circulatory system for slower organisms and a closed one for the movers. To digest food, there is the evolved structure known as the radula, and the siphon in organisms such as the squid. The nervous system of a Mollusc also exhibits a more advanced and true brain, as well as a pair of eyes. We also see the gill structure again, but they are more advanced and true as well.
In the Arthropods, we see true segmentation with specialization, as well as a tough exoskeleton made of chitin, jointed appendages, a jointed cephalothorax, and the process of molting. For circulation, we see the first true heart, and several types of special mouth parts of digestion. Arthropods also excrete wastes using their malpighian tubes. They also have a more advanced nervous system, with coordination due to their appendages, and a new structure called a compound eye. For respiration, Molluscs use new evolved tracheal tubes, and organisms like spiders use book lungs.
Echinoderms are the first organisms to show pentagon-radial symmetry, and an internal skeleton instead of an external skeleton that we see in Arthropods. For circulation, they have a closed system, as well as a digestive gland that transports nutrients to the digestive cavity. They also have a new structure known as tube feet, which help with respiration, excretion, and movement.
The last group is the Chordates, which is wear we see the first vertebrates. This refers to how they have a true spinal cord. The lower chordates have a new structure called a notochord, as well as a dorsal nerve cord for a nervous system. They respirate using pharyngeal gill slits, and also have a post- anal tail that helps with movement. However, not all these traits are shown in the adult organism. The higher chordates also have a dorsal nerve cord that serves as a backbone, as well as an endoskeleton. Their notochord is also reduced in the adult form. However, they still use cephalization, and circulate using their closed circulatory system.
2. WHICH ANIMAL IS MOST ADAPTED TO LIFE ON EARTH?... In my opinion, the jellyfish is most adapted. As I learned from the National Geographic Film Jellyfish Invasion, they can live almost anywhere, and nobody really knows where they came from. One of the main advantages of a jellyfish is their stinging cell, called a cnidocyte. I explained how this works on my Explained Phyla Tab. Because of this stinging cell, jellyfish can obtain prey almost everywhere. Plus, it's a great line of defence. Out of the 30 thousand types of jellyfish, 70 are venomous to humans, but many of the other types are venomous to predators in the ocean. To tell the truth, jellyfish kill more people in Australia than sharks or crocodiles ever have. Considering they can kill humans, this means they can also kill other organisms and possibly obtain a food source from them. Jellyfish can also reproduce very easily. If people try to get rid of them by slicing them up, it only releases more sperm and egg and produces millions more jellyfish. To add to that, the polyps can stay dormant on the bottom of the ocean for years, decades, or sometimes even half a century. So even if someone thinks the jellyfish population has died off, the polyps may come back to bud in a few years or so. Jellyfish also may be difficult to be ingested by predators, because of their stinging cells. If a predator tries to eat the jellyfish, they will most likely get stung by the cnidocytes. Therefore, the jellyfish population will keep on growing since there aren't any predators to get rid of them. This is the same for jellyfish who exist in dead zones- the population will only continue to grow since nothing can inhabit that area but jellyfish. 3. IS MY PORTFOLIO A PIECE OF EVIDENCE FOR THE THEORY OF EVOLUTION?... Yes, I think my portfolio could contribute to the theory of evolution. As I explained in my Explained Phyla Tab and throughout the first topic on this tab, organisms have evolved hugely from sponges to fish. As evolution describes a change in characteristics, we see evolution through the ways the phylums change, and how they evolve new traits as we proceed. For example, the difference between a Porifera and a Cnidarian. For the Cnidarian to evolve, the DNA had to change, changing the genotype and therefore changing the phenotype as well. This is EVOLUTION! The Porifera is assymetrical, and as evolution occurred and the DNA changes, the phenotype changes and we see radial symmetry in the Cnidarian. This happened over and over to create new organisms, such as bilateral symmetry appearing in the Platyhelminthes.
There is also the fact of the dissections that I have documented. By dissecting a variety of organisms and posting the pictures with the lab, we can examine further the structures of organisms, as well as how their internal organs and bone structure are related. When looking at the four general pieces of evidence for evolution, homologous structures are included. This refers to the bone structure of organisms being similar. Because I included the dissections in my portfolio, they can contribute to the theory of evolution since they support the idea of homologous structures. Although I did not upload the rat and frog dissections, I was able to see some of the similar structure between those organisms and others I had previously examined. Judging from the evidence I have given, I can finalize that my portfolio would be a good piece of evidence towards the theory of evolution.