Final Question #1
Throughout this Semester, we done quite a few Dissections now. So to "Connect" all these dissections together, I will be giving detailed information about all the stuff we dissected and then comparing the all together to show how all of the animals have adapted to being what they are today.
Digestion:
Roundworm (Phylum Nematoda)
- Roundworms have 2 openings, 1 for ingesting , and the other for excreting wastes.
- They contain no stomach for storing food so the food just enters the mouth - pharynx - intestines - rectum - anus.
Earthworm (Phylum Annelida)
- Also have 2 openings
- When Roundworm eat the food go through the mouth - pharynx - esophagus - crop (stomach-like) - gizzard (small intestine) - long intestine - anus
Grasshopper (Phylum Anthropoda)
- Has 2 openings
- Mouth - pharynx - esophagus - crop - gizzard - anus
- Has 3 main parts; Foregut, Midgut, and Hindgut
- Foregut - enters the grashopper at the mouth where saliva breaks the food down as it enters the gizzard
- Midgut - Where the body start to absorb the nutrients by releasing digestive juices into the gizzard
- Hindgut - releases unabsorbed food by the anus
Starfish (Phylum Echinodermata)
- Has 2 openings
- Mouth - Stomach - Intestine - Anus
- The starfish pushes it's stomach out of its mouth and releases digestive juices onto it's prey
- From here, it absorbs it's partially digested prey into it's body with it's stomach and finishes the digestive process thanks to the Pyloric Caeca which is found in it's arms
- Excretes waste through anus
Grass Frog (Phylum Vertebrata)
- Has 2 openings
- Mouth - Pharynx - Esophagus - Stomach - Small Intestine - Large Intestine - Anus
- Similar digestive system to humans but instead they mainly feed on insects such as flies
Reproduction:
Roundworm (Phylum Nematoda)
- Have separate sexes for both male and female
- Internal Fertilization
- Can produce 200 000 during one time
- Are Hermaphrodites which mean that each roundworm contain both male and female parts
- Internal reproduction by releasing sperm into each other and enters their clitellum
- Cocoon forms on the end of the clitellum and soon the sperm retrieved from the other worm reaches their eggs and thus resulting in fertilization.
- Produces 3-5 worms each cocoon
Grasshopper (Phylum Anthropoda)
- Have Seperate sexes for both male and female
- Internal Fertilization
- Produces 8-25 offspring
- Newborns will undergo Metamorphisis (shedding skin) leading to maturity
Starfish (Phylum Echinodermata)
- Are Hermaphrodites
- Can reproduce Sexually by using it's gonads to release sperm and eggs into the water for external fertilization
- Can reproduce Asexually by Binary Fission which is the process of cutting/or a radial arm of the starfish falling and containing a gonad. From here the arm will grow a new body and the body will grow a new arm
Grass Frog (Phylum Vertebrata)
- Have Separate sexes for both male and female
- External Fertilization
- Can produce about 1000-4000 eggs at a time but only 1 out of every 2000 make it to adulthood
- Eggs are laid in water but after tadpoles reach maturity they can also live on land
Respiration:
Roundworm (Phylum Nematoda)
Earthworm (Phylum Annelida)
- Has no formal respiration
- Oxygen enters the body and releases CO2 by Difussion
- Have no lungs
- Breathe through their skin by diffusion.
Grasshopper (Phylum Anthropoda)
- Also do not have lungs
- Instead they have Spiracles located on the sides of the body which branches out to the trachea and where Oxygen and CO2 can be exchanged.
Starfish (Phylum Echinodermata)
- Have no lungs
- Have Ampulla found in it's arms which assist in respiration and circulation
Grass Frog (Phylum Vertebrata)
- Have lungs
- Respirate through lungs like humans
- Can also respirate through their skin which is why their skin is always so moist
Circulation:
Roundworm (Phylum Nematoda)
- Have no heart or blood vessels
Earthworm (Phylum Annelida)
- Have a close Circulatory system
- Have 3 main vessels Aortic Arches, Dorsal Blood Vessels, and the Ventral Blood Vessels
- Aortic Arches - pump blood into other 2 vessels
- Dorsal Blood Vessels - carries blood to front of the body
- Ventral Blood Vessels - carries blood to the back of the body
Grasshopper (Phylum Anthropoda)
- Has an Open Circulatory System
- This means that the blood does not transport itself throughout the body but instead just floats in the body not following a specific route
- Although it does not have a route, it does have an Aorta (Heart) which still pumps the blood to provide the circulation of blood.
Starfish (Phylum Echinodermata)
- Have a closed Circulatory system
- Have a Water Vascular System because they live under water
- Circulate water through the Madreporite found on the Aboral/ Top surface of the Starfish
Grass Frog (Phylum Vertebrata)
- Have a closed Circulatory System
- Circulates blood through by it's heart which branches out to many veins and arteries
- Very similar to Humans
Nervous System:
Roundworm (Phylum Nematoda)
- Have 2 nerve cords (Dorsal Nerve cord & Ventral Nerve Cord) that transmit impulses to various cells and tissues of the Roundworm's Body
Earthworm (Phylum Annelida)
- Has a simple nervous system which consists of a Celebral Ganglion, ventral Nerve Cord, and the Segmental Ganglions
- The Celebral Ganglion acts as the brain while the other 2 recieve the information and make the body move.
Grasshopper (Phylum Anthropoda)
- The Nervous system consists of the Brain, the Ventral Nerve Cord, the Eyes, and it's antennae
- The body is still able to walk and jump even though the brain has been damaged or been removed
- It's eyes and antennae are most important because grasshoppers mainly survive by the signals it receives by it's antennae.
Starfish (Phylum Echinodermata)
- Have no brain
- Only have eyespots on the end of each arm which is used for detecting it's surroundings
Grass Frog (Phylum Vertebrata)
- Has a brain which is connected to it's Spinal cord which then transport information to all parts of it's body
- And yes, it is very similar to the Human's Nervous System
Conclusion:
Now that we can see how each organism functions, we can now compare them to how they have technically evolved from each other. As you can see as you go down from the Roundworm all the way to the Grass Frog you can see the increase in complexity in all systems. For example from the Roundworm having no source of respiration, the Grass Frog has a complete set of lungs which is almost exactly the same as the humans. This is because Roundworms live in Intestines and have no need for oxygen but instead depend on their host for survival while on the other hand, Frogs are independent and need lungs in order to survive just like Humans! Given this information, I'd say that Frogs are much more successful in the environment because of how they can survive independently even though they may not be the biggest predator out there. So all in all, what I'm trying to say that evolution has mainly been based on habitats. For example, if we need something, our species would evolve to help that specific need and in this case frogs is much more evolved than the roundworm.
This means that in my perspective the Earthworm, Grasshopper, and Starfish are between the roundworm and frog based on their evolution and their traits through Natural Selection.
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