Lower Invertebrates
Bold text= advancement form the last Phylum
Phylum Porifera- Porifera meaning pore bearer, this phylum consists of sponges. In sponges there are specialized cells, but they don't work cooperatively, they have no true tissues and they are the most primitive(simplest) of the animals. With no tissue layers they rely on spicules and spongin for structural support. Sponges are asymmetrical, do not have a nervasystem and are filter feeders. They live in fresh and marine water, using the flow of water through their collar cell to get their nutrients. All sponges are sessile and reproduce both sexual and asexually. They reproduce sexually by the means of internal and external fertilization and asexually by budding and gemmules, which are groups of amebocytes that can withstand harsh conditions and when it is suitable can regrow a new sponge. Gemmules are made to ensure their species will live on even after harsh conditions.
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Phylum Cnidaria- Cnidaria meaning stinging creature, all the members of this phylum are equipped with stinging tentacles for hunting. These tentacles have cnidocytes on them that shoot out a harpoon like structure called a nematocyst when brushed up against. Cnidarians live in both fresh and salt water and can kill humans with the toxins contained in their nematocysts. Cnidarians are both motile and sessile, meaning they have both moving and stationary parts of their lives. They go through a transformation called "Alternation of Generations" where they spend some of their life in the motile medusa stage and some of their life in the sessile polyp stage. Cnidarians have radial symmetry, a nerve net with simple eyes and two tissue layers meaning they are diploblastic. These two tissue layers are the ectoderm(outside layer) and the endoderm(inside layer). Cnidarians reproduce sexually with motile gemmetes and asexually in the form of regeneration and budding. There are three different classes within phylum Cnidaria which are Hydrozoa, Anthozoa and Scyphozoa. They all go from being a planula larva to a developing polyp on the ground which then matures and buds off young medusa that grow and send out motile gammetes to go from more planula larva. In class Hydrozoa the polyp stage is dominant and some examples are Hydras and Obelias. In class Anthozoa the polyp stage is dominant and examples are anemones, corals and sea pens. In class Scyphozoa the medusa stage is dominant and it includes the jellies.
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Phylum Platyhelminthes- Platyhelminthes, otherwise known as the flatworms is the first phylum to be triploblastic, meaning it has three tissue layers. The three layers are the ectoderm, mesoderm and the endoderm. Flatworms are acoelomates meaning they have no body cavity, frankly because they are flat and have no room for one. This phylum is the first to have bilateral symmetry and a primitive brain called a ganglia. Platyhelminthes is the first phylum to have a separate mouth and excretory system. They don't have a true anus yet, but they have these things called flame cells which excrete waste out of pores in their skin. They are equipped with a nerve ladder and they have cephalization. There are three classes within Platyhelminthes, class Turbellaria, class Trematoda and class Cestiodea. Class Turbellaria is not parasitic, so they have eyespots and auricles, an example of this class is the planaria. Class Trematoda consists of parasitic flukes including the liver, blood, lung, heart, and intestinal flukes. They are parasitic so they don't have eyespots because they are not needed and have both a primary and intermidiate host. Class Cestiodea are the tapeworms and are also parasitic and have developed hooks and suckers on their scolex to attach to the linings of intestines. Flatworms reproduce both sexually by proglottids and penis fencing and asexually through fission and regeneration. All flatworms are hermaphroditic.
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Phylum Nematoda- More commonly known as round worms are the first animals to have a tube within a tube body plan. This means the have separate mouth and anus, a complete digestive system, triploblastic, and they are psodocoelomates. The psodocoelom (fake body cavity) is between their mesoderm and endoderm layers. They have bilateral symmetry and are both free-living and parasitic. There are many species of Nematodes some are ascaris, necator(hookworms), enterobius(pinworms), trichinella, filarial worms, and the guinea stick worm. All of those are parasitic Nematodes, the terrestrial Nematodes are decomposers. Nematodes are not hermapherodites so they can only reproduce sexually through internal fertatization. They have only two nerve cords, a dorsal and a ventral cord. Most Nematodes live majority of their lives in humans. This phylum is the most disgusting for sure!!
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4. Parasites: They have changed to live in the intestines of other animals and humans. They don't not have eyespots or auricles like their terrestrial ancestors because they don't need to find food or get around. Over time they have developed hooks and suckers on their scolex(head) to attach to the intestines of their host. They use their suckers to not only to attach, but they use them to suck nutrients for their host and often make their host malnourished. Some parasites have developed these things called proglottids that have ovaries and testis inside and cross fertilize with another parasite with proglottids. after the cross fertilization the proglottids drop off and get into feces of other animals to come across and be infected by them. There is nothing good about being infected by a parasite.
Free-living: They have developed things like eyespots and auricles to help them find food and get around. They have cilia to be able to move and swim depending on where they live. They have a penis to be ably to penis fence when reproducing. They have developed an array of colours for protective because most fish know bright colours means poison. Free-living worm look very different from parasitic worms. Free-living worms are usually not as long as parasitic worms and are usually a lot prettier as well.
Free-living: They have developed things like eyespots and auricles to help them find food and get around. They have cilia to be able to move and swim depending on where they live. They have a penis to be ably to penis fence when reproducing. They have developed an array of colours for protective because most fish know bright colours means poison. Free-living worm look very different from parasitic worms. Free-living worms are usually not as long as parasitic worms and are usually a lot prettier as well.
5. Necator americanus- I chose the hookworm because I hate feet and the thought of a worm burrowing into feet truly disgusts me. The hookworm larva penetrates the skin between your toes and if it can't get in easily it will excrete a fluid that makes you itch and scratch off some skin to make it easier for them to get in. Once inside the larva finds its way to the blood stream and takes that to your lungs where it grows. When it is grown it is coughed up and swallowed. It enters your intestines where it drains your blood and can reproduce and the new larva leaves your body in your feces. They cause malnourishment in humans and to prevent getting infected you have to wear shoes or socks. They are very dangerous in kids because it can lead to physical and mental retardation.
Ascaris Dissection |
Higher Inertebrates
Annelida
Analysis:
What is the name of the pumping organs of an earthworm? The pumping organs of an earthworm are called aortic arches and there are five pairs of them. In the earthworm, trace the parts of the digestive tract through which food passes. Prostomlum, mouth, pharynx, esophagus, crop, gizzard, intestines, anus Which of the parts of the earthworm's body that you saw are included in the excretory system? The two parts that we saw were the anus and the nephridias. Among the earthworm's structural adaptations are its setae. How do you think the earthworm's setae make it well adapted to its habitat? The setae help the earthworm from not slipping and help them move, so in the mud the setae keep the worm moving forward. How is the earthworm's digestive system adapted for extracting relatively small amouts of food from large amouts of ingested soil? Earthworms are equipped with a gizzard that breaks down the food for more surface area to be digested. They also have very long intestines which give the food a lot of time to be digested as well. What did each germ layer develop into in the earthworm? The ectoderm turns into the skin and nerve system,the mesoderm turns into the muscles and organs and the endorderm turns into the digestive system. What is the function of the nephridium? How does it complete this function? Nephridium are excretory organs which filter fluid in the coelom and acts like a kidney. How is the sandworm similar and different to the earthworm? Sandworms are different then earthworms because they have many setae, they are from different classes and they have parapodia where as earthworms don't. they are the same because they both have a true coelom, they are both segmented, they both have a complete digestive system and they both are part of phylum Annelida. How is the leech designed to live as an ectoparasite? What are the similarities and differences between the leech and the earthworm? The leech has a large crop for blood, has both anterior and posterior suckers, has small eyes and has jaws with ridged teeth. The are different then earthworms because the are parasites, they have no setae and they only feed on blood. Leeches are the same as earthworms because they are in the same phylum, they both have cephilization and they both have true coeloms. |
Earthworm DissectionSandworm |
Mollusca
Analysis:
How are the arms and tentacles similar and different? They both are abated from the foot and they both have small hooks. They are different in length, the tentacles being much longer than the arms. The tentacles lack sucker but instead have a sticky, mucus-like covering. The tentacles are used for grabbing and holding on to prey and also play a roll in reproduction, where as the arms are mainly for aiding food to the mouth to be eaten. How are cephalopods similar and different to bivalves? The cephalopods are highly evolved and have an inner shell, where as the bivalves are less evolved and have two hard outer shells. Cephalopods have highly adapted brains and eyes and bivalves are not that advanced. Bivalives are filter feeders and mostly seesile and cephalopods are all motile and feed off of other animals. The two classes are both part of the phylum Mollusca, they are both triploblastic and both have hard shells. Was your squid a boy or girl? How did you determine this? Our squid was a female. We could tell because of the eggs in her ovary. The males have a milky substance where we found the eggs and this is the squids sperm. Trace the path of food through your squid. Once the squid captures it pray the food enters it's body past the beak and in the mouth. The food then travels through the squids digestive glands to it's stomach, where it as digested.The nutrients are taking into the blood and spread throughout the body. The leftover waste is excreted out the anus located above the head of the squid. Why are the brachial hearts so close to the gills? The gills act as lungs and the hearts get oxygen from the gills to be pumped throughout the body in the blood stream. Because the hearts are so close to the gills there is less distance for the oxygen travel there of making it to the hearts faster. This means the muscle of the squid can receive oxygen fast and then the squid can move faster. |
Squid Dissection |
Arthropoda
Analysis:
How many pairs of appendages did your crayfish have? Me and my partner counted 24 appendages, so 12 pairs. How does the thickness of the exoskeleton around the joint compare with the thickness around the rest of the leg? The thickness around the joint is much thinner than the thickness of the rest of the leg, because the joint only has tendons and a little bit of muscle and the exoskeleton can't be thick there because it needs to allow for mobility. What was the sex of your crayfish and how did you know? Our crayfish was a male and we knew this because the first swimmerets were thick and tube-like. These are used to hold sperm and grab onto the female while mating. The first swimmerets on a female are soft and hair-like and are used to hold eggs. Why is there so much surface area on the gills of a crayfish? The abundance of surface area allows for more gas exchange to occur at once. Which appendage is used to... -sense: Antennae, Antennules, Compound eyes. -defend: Chilped -mate: Swimmerets, Sudopenis -eat: Maxilla -chew: Mandibles -move backwards: Tail -move forwards: Walking legs -swim: Telson, Urapods, Swimmerets How are arthropods more advanced than other phyla that we have looked at thus far? Arthropods are more advanced because they have an exoskeleton, a hemocoel, lungs for on land, malpighian tubes, social behaviours and specialized appendages like walking legs, swimmerets and wings for flight. Why are the insects so prolific while the crayfish are not? Insects are more prolific because they are very small or even minute so they don't need to eat very much, they have the ability to fly and cover more land at once and they have a specialized niche. This means each different insect have its own job to do like in honey bees there are worker bees and a queen bee and helpers for the queen and so on. This helps make less competition to fight for the same niche. |
Crayfish Dissection |
Echinodermata
Analysis:
What type of symmetry did your sea star have? All normal sea stars that haven't had arms cut off have penta-radial symmetry. How many arms or rays does your sea star have? Almost all sea stars are five arms or rays as long as they haven't had one cut off. What is the upper surface of the starfish called? The upper surface of a sea star is called the aboral surface because the mouth is not on this side. What is the lower surface of the starfish called? The lower surface of a sea star is called the oral surface because the mouth is located on this side. Trace the path that water takes through the starfish. Water enters the starfish through the madreporite, goes down the stone canal to the ring canal and out in to the arms in the lateral canals. On which surface are these parts of a sea star visible: Mouth- Oral Madreporite- Aboral Suckers- Oral Oral Spines- Oral Eyespots- Aboral Ambulcaral Groove- Oral What part of the tube foot creates suction to open clams whenever the sea star feeds? The ampulla part of the tube feet has the ability to make the tube feet suction or not. Water is pushed past the ampullas and make the tube feet suction enough to be able to pry open a clam. Why do the gonads sometimes appear larger? In mating season the gonads are very large and take up most of the inner arm, where as in the off season they are very small and often can even be see. What type of skeleton does the sea star have? Starfish have what's called an endoskeleton which means skeleton on the inside. Just under their skin and spines they have many small bones connected by muscles to allow of movement. What bony plates make up its skeleton? The bony plates the make up its skeleton are called ossicles. What is the function of the pyloric caeca? The function of the pyloric caeca is to produce enzymes to help digestive processes in the stomach. Where is the stomach of a sea star located? What can the sea star do with its stomach when feeding on clams and oysters? The stomach is located in the middle of the sea star, under the central disc. When a starfish is eating it can push its stomach out of its body through the mouth. The stomach is pushed into the clams and it slowly digests the clam. When its done digesting, the stomach is pulled in through the mouth and back into the starfish. |
Starfish Dissection |