Poriferans vs. Cnidarians
Cnidarians vs. Platyhelminthes
Platyhelminthes vs. Nematoda
Parasite vs. Free-Living Worm
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Free living worms tend to live in soil and water whereas a parasitic worm typically lives inside of a host. Class Turbellaria are free living worms unlike the classes Cestoda and Trematoda which retain parasitic worms. A free living worm is a decomposer, meaning that it breaks down waste and other organic materials. A parasitic worm mainly feeds off the nutrition and food of its host. In fact, a parasitic worm is completely reliant on its host so it doesn't need to be as developed as a free living worm. A parasitic worm doesn't have eye spots, auricles, a ganglia/primitive brain, nerve cords or a pharynx, which are key aspects which help free living worms such as Turbellaria from phylum platyhelminthes to survive. However the key distinction between the two for me, is the fact that parasitic worms are usually harmful, in contrast to free living worms which don't generally have much of an effect at all.
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The Filial Worm
The filial worm is particularly disgusting because of what it does to its host. It's a very small nematode that blocks and lives in lymph ducts. Since they're blocked, fluids accumulate because they can't drain resulting in malformation and critical swelling below where the worm is. It results in Elephantiasis or Lymphedema. The condition is called Lymphatic filariasis and it infects more than 120 million people in over 73 different countries. Luckily, they aren't in North America but are located in parts of Asia, Africa, the Caribbean, Western Pacific and South America. The disease is spread by pesky mosquitos. If a person is infected, an adult worm lives between 5 and 7 years in the body of it's host... you. When the adult worms mate, they have millions of microfilariae which are microscopically small worms. When a mosquito bites a person with infected blood, it passes the disease on to the next person. The only preventative measures a person can take is avoid being bitten by a mosquito. Use a mosquito net and wear lots of bug spray as well as wear clothing that cover most exposed skin. The treatment for this condition is a medicine called diethylcarbamzine, or DEC. This doesn't kill adult worms, just the babies and prevents you from infecting anybody else.
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Worm Dissection
- What is the name of the pumping organs of an earthworm? The 5 aortic arches are the pumping organs of an earthworm and act similar to our hearts pumping motion.
- In the earthworm, trace the parts of the digestive tract through which food passes. First the food enters through the mouth, then passes through the pharynx and esophagus. Next it enters the crop which acts as a storage compartment, softening it and obtaining nutrients. Then the food enters the gizzard where it is crushed up and made easier for digestion in the intestine.The waste is then excreted out the worms anus.
- Mouth-Pharynx-Esophagus-Crop-Gizzard-Intestine-Anus.
- Which of the parts of the earthworm’s body that you saw are included in the excretory system? The only parts of the excretory system that were visible was the nephridia and anus.
- Among the earthworm’s structural adaptations are its setae. How do you think the earthworm’s setae make it well adapted to its habitat. Setae were a very useful adaptation because they allow the earthworm to grasp the soil to get traction and push itself through the soil quicker.
- How is the earthworm’s digestive system adapted for extracting relatively small amounts of food from large amounts of ingested soil? Earthworms have long intestine and a crop which stores the food, softening it and the gizzard which grinds it up increasing the foods surface area, obtaining nutrients.
- What did each germ layer develop into in the earthworm? The ectoderm develops the skin, ganglia and nerve cord. The mesoderm develops the muscle and reproductive systems and the endoderm creates the guts such as the intestine, crop and gizzard.
- What is the function of the nephridium? How does it complete this function? Nephridium are excretory organs that filter fluids in the coelom. Help eliminate waste containing Nitrogen.
- How is the sandworm similar and different to the earthworm? Parapodia are seen on a sandworm and not an earthworm. Sandworms are scary looking whereas earthworms aren't. Sandworms (class Polychaeta) have lots of setae and earthworms (class oligochaeta) have few. Earthworms have citellum. Both worms however are segmented, have a coelom and have a mouth/anterior end.
- How is the leech designed to live as an ectoparasite? What are the similarities and differences between the leech and the earthworm? A leech is designed to be an ectoparasite because they have suckers on both ends that they use to latch on to prey and suck the blood out. A leech and earthworm are in different classes, and an earthworm is segmented whereas a leech isn't. Both have an outside layer, inside layer and are coelomates.
Squid Dissection
1. How are arms and tentacles similar and different? There are only 2 long arms in comparison to the 8 shorter tentacles of a squid. Arms only have suckers at their ends whereas tentacles have suckers running all the way down which gives a really good grip on their prey and guides it to their mouth. The arms are what initially grabs onto the food and can also be used to assist in mating.
2. How are cephalopods similar and different to bivalves? Although the shell of cephalopods are greatly reduced, both classes technically have a shell, bivalves having 2. Bivalves are filter feeders and sessile which is drastically different than cephalopods who are the largest invertebrate, motile predators. Vertebrate eyes and the capability of learning are both qualities that are present in cephalopods but are lacking in bivalve organisms.
3. Was your squid a boy or girl? My squid was clearly a girl because she had a hard translucent yellow sack at the posterior end of her body. This would be her ovary and if you check the picture, the eggs inside are visible.
4. Trace the path of food through your squid. The prey is first eaten through the mouth and follows the digestive tract through the digestive glands and into the stomach. In the stomach nutrients from the food are extracted and the waste exits through the anus.
5. Why are the brachial heart so close to the squid? The brachial heart is so close to the gills because it is much closer to where oxygen enters the body. This makes it much faster for the heart to obtain oxygen and is overall more efficient.
2. How are cephalopods similar and different to bivalves? Although the shell of cephalopods are greatly reduced, both classes technically have a shell, bivalves having 2. Bivalves are filter feeders and sessile which is drastically different than cephalopods who are the largest invertebrate, motile predators. Vertebrate eyes and the capability of learning are both qualities that are present in cephalopods but are lacking in bivalve organisms.
3. Was your squid a boy or girl? My squid was clearly a girl because she had a hard translucent yellow sack at the posterior end of her body. This would be her ovary and if you check the picture, the eggs inside are visible.
4. Trace the path of food through your squid. The prey is first eaten through the mouth and follows the digestive tract through the digestive glands and into the stomach. In the stomach nutrients from the food are extracted and the waste exits through the anus.
5. Why are the brachial heart so close to the squid? The brachial heart is so close to the gills because it is much closer to where oxygen enters the body. This makes it much faster for the heart to obtain oxygen and is overall more efficient.
Crayfish Dissection
1. How many pairs of appendages did your crayfish have? 15 pairs.
3. How does the thickness of the exoskeleton around the joint compare with the thickness around the rest of the leg? At the joint the thickness of the exoskeleton is very thin to allow for a higher range of movement and because it is mainly muscles and tendons.
4. My crayfish is a female. I know this because: the swimerettes are soft and feathery feeling.
5. Why is there so much surface area on the gills of a crayfish? Its an adaption, when diffusion takes place the more surface area the better.
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3. How does the thickness of the exoskeleton around the joint compare with the thickness around the rest of the leg? At the joint the thickness of the exoskeleton is very thin to allow for a higher range of movement and because it is mainly muscles and tendons.
4. My crayfish is a female. I know this because: the swimerettes are soft and feathery feeling.
5. Why is there so much surface area on the gills of a crayfish? Its an adaption, when diffusion takes place the more surface area the better.
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7. Which appendage(s) is used to:
8. How are arthropods more advanced than the other phyla that we have looked at thus far? Arthropods are more advanced so far because they have specialized segmented bodies, an exoskeleton, all reproduction is done sexually and there are no hermaphrodites, they have 1 developed heart, a complex mouth with specialized appendages for feeding and some of these organism have book lungs or tracheal tubes.
9. Why are the insects so prolific while the crayfish are not? Insects are so successful because:
- sense compound eye, antennae, antennules
- defend chelipedes
- mate pseudo penis for males, modified swimmerettes for females
- eat chelipeds
- chew maxillpeds
- move backwards tail
- move forwards legs
- swim swimmerettes
8. How are arthropods more advanced than the other phyla that we have looked at thus far? Arthropods are more advanced so far because they have specialized segmented bodies, an exoskeleton, all reproduction is done sexually and there are no hermaphrodites, they have 1 developed heart, a complex mouth with specialized appendages for feeding and some of these organism have book lungs or tracheal tubes.
9. Why are the insects so prolific while the crayfish are not? Insects are so successful because:
- They're small-don't eat much and can hide
- Exoskeleton-hard and provides strength
- Short life span-don't eat much
- Reproduction-all sexual which means a diverse population
- Flight-lots of advantages
- Specialized appendages-eat a variety of food
- Exoskeleton adaptations-camouflage
- Well developed senses
- Social behaviours and habits
- Specific niches minimizing competition
Starfish Dissection
1. What type of symmetry did your sea star have? It had pentaradial symmetry.
2. How many arms does your sea star have? Sea stars have 5 arms.
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2. How many arms does your sea star have? Sea stars have 5 arms.
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4. What is the upper surface of a starfish called? Its called the aboral surface.
5. What is the lower surface if the starfish called? It's called the oral side because it's the side of the sea star with a mouth.
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5. What is the lower surface if the starfish called? It's called the oral side because it's the side of the sea star with a mouth.
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9. Colour an arrow on the diagram above tracing the path the water takes when it enters and moves through the sea star.
10. On which surface are these parts of a sea star visible:
a) Mouth: Oral surface
b) Madreporite: Aboral surface
c) Suckers: Oral surface
d) Oral Spines: Oral surface
e) Eyespots: Aboral surface
f) Ambulcaral groove: Oral surface
11. What part of the tube foot creates suction to open clams whenever the sea star feeds? The sucker at the end of the tube foot creates suction to help the starfish open clams to eat and also aid in walking/movement.
12. Why of the gonads sometimes appear larger? The gonads tend to appear larger during mating season to make room to store lots of eggs and sperm. During the rest of the year, the gonads are small which is why we couldn't find them during our dissection.
13. What type of skeleton, endoskeleton or exoskeleton, does the sea star have? Sea stars have a semi-flexible endoskeleton.
14. What bony plates make up its skeleton? Ossicles, which look a lot like ribs.
15. What is the function of the pyloric caeca? Its attached to the pyloric stomach and makes digestive enzymes which aid in feeding.
16. 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 central disk of a sea star. The stomach can invert itself to get inside of a clams shell to eat and digest it.
10. On which surface are these parts of a sea star visible:
a) Mouth: Oral surface
b) Madreporite: Aboral surface
c) Suckers: Oral surface
d) Oral Spines: Oral surface
e) Eyespots: Aboral surface
f) Ambulcaral groove: Oral surface
11. What part of the tube foot creates suction to open clams whenever the sea star feeds? The sucker at the end of the tube foot creates suction to help the starfish open clams to eat and also aid in walking/movement.
12. Why of the gonads sometimes appear larger? The gonads tend to appear larger during mating season to make room to store lots of eggs and sperm. During the rest of the year, the gonads are small which is why we couldn't find them during our dissection.
13. What type of skeleton, endoskeleton or exoskeleton, does the sea star have? Sea stars have a semi-flexible endoskeleton.
14. What bony plates make up its skeleton? Ossicles, which look a lot like ribs.
15. What is the function of the pyloric caeca? Its attached to the pyloric stomach and makes digestive enzymes which aid in feeding.
16. 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 central disk of a sea star. The stomach can invert itself to get inside of a clams shell to eat and digest it.