Sunday, October 14, 2007

Yep, Its the Animal Kingdom

Hey Period 8 and 9! This was what Friday’s lesson was on:

The Animal Kingdom is the final kingdom of the Eukarya Domain along with the Protists, Plants and Fungi. What makes the Animals special from the other 3 Kingdom's you ask? Well first of Animals are Heterotrophs, in which the ingestion of other organisms is need in order for nutrients to be obtained. Secondly Animals have extreme complex bodies and their cells do not contain a cell wall, which allows for active movement to take place. Thirdly, Animals partake in Sexual Reproduction in which 2 organisms male and female mate with each other (Cool! just like these Turtles!). There is no alternation of generations nor are there Haploid Gametophytes. Animals stay Diploid for most of their life cycle with the exception of gamete production in which the Gametes, namely an Egg and Sperm are haploid.

Now, all animals came from one Ancestral Protist. From the Eukaryotes came the Animals and the first step of Animal Evolution wass Multicellularity. From there the Porifera group of more commonly known as sponges became apparent. Porifera's were primitive animals. They are invertebrate animals or have no back bone or spinal cord. Sponges were primitive because they lacked any distinct tissues organ but had specialized cells in them and were the only animals without organization. Porifera obtained its food by the process of Endocytosis or infolded its cell membranes like and Amoeba. Sponges have no symmetry what so ever.

Along with the appearance of Porifera's, step 2 came about in evolution by branching off of mulitcellularity and the introduction of tissues. Next came the Cnidarian’s or the Jellyfishes, Hydra, Sea Anemone and Corals. The Cnidarian group contained Tissues but no organs and had not one but two cell layers, outside and in, and Cnidaria's like the Porifera's are invertebrates in which they have no spinal cord. They are predators because the Hydra, Sea Anemone and Jellyfishes contain stinging cells on their tentacles surrounding their gut openings and had extracellular digestion in which enzymes are released into the gut cavity, break down the meal and spit the waste out the way it came in (Ew, that must smell horrific) . Cnidarian’s are radically symmetrical in which if the organism was cut in half in any direction the opposing half would be exactly the same. (I Do Not recommend being stung but one of these creatures apparently they are not a very good thing and happen to be extremely painful and annoying, thanks Tom)

Step 3 came about in Animal evolution with the branching off of Bilateral Symmetric organisms and the introduction of the Platyhelminthes otherwise known as the Flatworms! (Gross creatures). Once again these organisms are invertebrates. Tapeworms and Planaria are examples of Flatworms. Flatworms are mostly parasitic creatures and don’t need to digest food just absorb it. They are also bilaterally symmetrical meaning they have a mouth and an anus. To be bilaterally symmetrical allows for a high level of specialization within parts of the body of an organism, which is a MAJOR advantage. On the next step of Animal evolution was the branching off of organisms that contained body cavities in which the outside world was separated from the inside one. These newfound organisms are called the Nematoda group or the Roundworms (once again gross!). Like their flatworm cousin they are bilaterally symmetrical (have mouth and anus) and contain a complex and well-developed digestive system. Like their flatworm cousin they are also parasitic organisms for example the Hookworm or the Nematodes. (I hope to never experience these creatures, ever).
* This next stop is much more complicated! As there are 2 different branches created leading to different groups of different qualities.

The 1st branch is the Segmentation branch and the 2nd the Endoskeleton branch each branch having its own separate mini-branches. So lets talk about branch #1. Branch 1 which is Segmentation contains three mini-branches, Mini-Branch #1 being the Mollusca group (Mollusks). Clams, Snails and Squids are part of this group. Once again they are invertebrate animals and are bilaterally symmetrical (there are few exceptions of course). Most of these organisms have soft bodies being protected by hard shells. These organisms have a true Coelem or an internal digestive cavity separated from everything else. This is an advantage because when bilateral organisms eat they could be eating other harmful things and separating that from your body can help lots! Mini-Branch #2 is the Annelida group. These are the Segmented worms such as the earthworms, fan worms and the leeches. They are, like Mollusks, bilaterally symmetrical and contain a true coelem or internal digestive tract. However the segments on each organism are not specialized to serve a purpose. They are also invertebrates. The Final Min-Branch, #3, is the Arthropoda group. These are such organisms as the spiders (Yuck!), insects and crustaceans (lobsters and crabs).
Arthropods happen to be the most successful animal phylum because there are more of them than any other animal on Earth. Yes, they are bilaterally symmetrical and are invertebrates. Arthropods are segmented creatures therefore making jointed appendages possible. Also they have an exoskeleton made of Chitin + Proteins. That’s the hard shell you have to crack through when you’re at Red Lobster treating yourself to a nice expensive meal. (Unfortunately I’m too cheap to spend my money on dinner). In the Arthropod group there are the Arachnids, containing 8 legs and 2 body parts (Spiders, Ticks and Scorpions)
, the Crustaceans, containing Gills, and 2 pairs of antennae (Crabs, Lobsters, Barnacles and Shrimp),
and finally the Insects, containing 6 legs and 3 body parts (You should know what an insect is). Well that’s the Segmented Branch of phylum’s. On to Branch # 2! Yay! Branch #2 (Almost Done!) which is the Endoskeleton groups contains only 2 mini-branches. Mini-Branch # 1 are the Echinodermatas most commonly known as the Starfishes, Sea Urchins and Sea Cucumbers.

These creatures are different from others because they are no longer bilaterally symmetrical, they are radially symmetrically. Remember what that is? Well in other words if this organism was cut in half in any direction the opposing side would be exactly the same or symmetrical. Echinodermata's also have spiny exoskeletons. Finally! Here we are! The final min-branch, #2, are the Chordates otherwise known as the Vertebrates, in which each organism contains a spinal cord or back bone unlike invertebrates do. Vertebrates also contain and internal bony skeleton and have a skull that encases the brain and have a backbone encased in a spinal column. There are many different kinds of vertebrates for example fish, reptiles, amphibians, birds and mammals (<---- cool us!).
Our first examples of Vertebrates are Fish (Trout, Sharks and Salmon). Fish appeared over 450 MYA on Earth.

Fish happen to have a bony and cartilaginous skeleton, scales, fins and jaws equipped to their bodies. Fish have gills in order to perform gas exchange under the water. Fish are different from so vertebrates because they only have a two-chambered heart meaning a singled loop of blood being circulated throughout its body. This quality is given a name. It is called being Ectothermic in which the blood of the organism is the same as the outside of the organism (Temperature-wise). Fishes partake in external reproduction in which fertilization takes place outside of the body in the water (the embryo also develops in the water in a aquatic egg casing (Think Finding Nemo).

*Fishes evolved into land creatures called Tetrapods meaning four limbs. An example of this so-called transition organism is Tiktaalik roseae (Yes, we read about him a couple of weeks ago).

Our second examples of vertebrates are Amphibians (Frogs, Salamanders and Toads). Amphibians appeared over 350 MYA on Earth.

Amphibians, unlike fish have legs and are tetrapods. They also had moist skin meaning they needed to live near water in order for gas exchange to be possible by diffusion through the skin. This was because the lungs had positive pressures put on them and were inefficient. Amphibians were also different from fish because they contain a three-chambered heart in which the veins traveled from the lungs back to the organism’s heart. They are similar to fish because they are also ectothermic and partake in external reproduction (fertilization is outside of organism). But amphibians such as frogs have offspring that metamorphosize from tadpoles to adults.

The third examples of vertebrates are the Reptiles (Dinosaurs, Turtles, Lizards, Snakes, Alligators and Crocodiles). Reptiles appeared over 250 MYA on Earth.

They are very different from our first two vertebrates. For example reptiles have drier skin, scales and armor on their external body. They also have lungs for gas exchange and use thoracic breathing or negative pressure (unlike fish or amphibians). But Reptiles are similar because they are Ectothermic creatures and have a three-chambered heart. Reptiles partake in internal fertilization but have offspring that develop externally in an amniotic egg. In this egg there is a structure called a Allantois, which allows for the exchange of gas to occur.

The Fourth examples of Vertebrates are Birds (Finches, Hawks, Ostriches, Turkeys and Chickens). Birds appeared 150 MYA on Earth. Birds happen to be very different from the other three vertebrate groups. Birds have feathers and wings on their bodies and contain an endoskeleton of bones that are thin and hollow allowing to flight to be possible.

Birds are also different because they have extremely efficient lungs and air sacs. Birds are Endothermic creatures (the complete opposite of Exothermic creatures making birds very different) and have a four-chamber heart containing 2 ventricles and 2 atriums. Birds are similar to reptiles because they reproduce through internal fertilization and have offspring develop in an amniotic egg.

Our fifth and final vertebrate group appeared 65 MYA on Earth, with the extinction of the Dinosaurs, Mammals! (Finally, Humans,!) When the dinosaurs went extinct, many niches were needed to be filled giving mammals a great opportunity. Mammals have specialized teeth and have hair. Like birds, mammals are endothermic and have a four chambered heart, 2 atriums and 2 ventricles. Like birds and reptiles mammals contain lungs and have negative pressure (Mammals also possess a diaphragm). What makes Mammals special from the rest of the vertebrate groups is the fact that mammals not only reproduce by fertilizing internally our offspring develop internally as well in a uterus where nourishment occurs through a placenta making the offspring live young. Mammals also have mammary glands to feed their young after they have been born (Yes, Breastfeeding just like the woman on the subway lol).

* Vertebrates also have many subgroups. For example there are the Monotremes, which are egg-laying mammals. Only the Duckbilled Platypus and the Echidna and a minute number of mammals partake in this process. There are the Marupials, which are pouched mammals. The offspring have a short-lived placenta therefore the parent needs a pouch in order to care for its young by sheltering it. Kangaroos, Opossums and Koalas are known for this. The last examples of a mammalian sub-group are the Placental mammals. These mammals are the true placenta users for example the Shrew, Bat, Whale and Humans.

Well that’s it guys so thanks for reading, hope its helpful enough. The sherpa for Monday night will be Saad. Sorry Saad Man lol


cara said...

I'm in an AP Bio class in MA and this guide is really helpful. Thanks for posting :D

lynn said...

I don't think I could have done it without this! Thank you so much. It was fun too! :)