Lower Invertebrates
phylum porifera
Porifera are the first multicellular animals. They have specialized cells, but no true tissues or organs. These are the simplest, most primitive animals. Porifera are also known as the sponges and they have changed very little since they evolved.
Here is a diagram of a sponge:
Here is a diagram of a sponge:
The outer layer of the sponge is made up of pinacocytes, which are epithelial cells. These are the sponge’s “epiderm”.
Water is essential to a sponge’s survival. Water carries nutrients and sperm from other sponges into the sponge while also carrying wastes and sperm from the sponge out into the environment. Water enters via pores called ostria and exits out of the top opening called the osculum.
A sponge is a filter feeder. They have flagellated choanocytes (also called collar cells) that line the spongocoel. The flagella of the collar cells create a wave that causes a current of water to flow through the sponge. While creating this current, the cells also capture food particles from the water. The food particles travel through the choanocytes and into the amoebocytes which digest them. Amoebocytes then carry the nutrients to the other cells in the sponge.
For structural support, sponges have spicules and/or spongin. Spongin is a form of collagen and spicules are like a skeleton for the sponge.
Sponges reproduce sexually and asexually. They reproduce asexually through gemmules. Gemmules are groups of amoebocytes that form when there are environmental pressures that threaten the sponge’s survival. When the sponge reproduces sexually, some of the choanocytes become sperm and some of the amoebocytes become eggs.
Water is essential to a sponge’s survival. Water carries nutrients and sperm from other sponges into the sponge while also carrying wastes and sperm from the sponge out into the environment. Water enters via pores called ostria and exits out of the top opening called the osculum.
A sponge is a filter feeder. They have flagellated choanocytes (also called collar cells) that line the spongocoel. The flagella of the collar cells create a wave that causes a current of water to flow through the sponge. While creating this current, the cells also capture food particles from the water. The food particles travel through the choanocytes and into the amoebocytes which digest them. Amoebocytes then carry the nutrients to the other cells in the sponge.
For structural support, sponges have spicules and/or spongin. Spongin is a form of collagen and spicules are like a skeleton for the sponge.
Sponges reproduce sexually and asexually. They reproduce asexually through gemmules. Gemmules are groups of amoebocytes that form when there are environmental pressures that threaten the sponge’s survival. When the sponge reproduces sexually, some of the choanocytes become sperm and some of the amoebocytes become eggs.
Phylum porifera lab
Analysis Questions
- Water enters through the ostrum. The flagella of the collar cells create a wave that causes a current of water to flow through the sponge.. Water exits through the osculum.
- Water carries nutrients that the sponge filters out and digests. Water also carries sperm in and out of the sponge and carries wastes out.
- They reproduce asexually by producing gemmules. They also reproduce sexually. The choanocytes are the sperm and the amoebocytes (also called archeocytes) are the eggs. The sperm exit via the osculum and sperm from other sponges enters via the ostrum. The zygote is expelled from the sponge.
- Spicules and/or spongin.
phylum cnidaria
Characteristics:
- Cnidarians are more advanced that Poriferans.
- They have true tissues and are diploblastic, meaning they have an ectoderm and an endoderm. They have a grouping of cells between the ectoderm and endoderm called the mesoglea. It is not, however, true tissues, just cells. The ectoderm makes up the skin and the nerves.
- Cnidarians have what is called a “nerve net”, meaning that the nerves are arranged randomly. They do not possess a brain. On the ectoderm, there are also two other types of cells: statocysts and ocelli. Statocysts detect gravity so the organism can stay upright, and ocelli are similar to eyes in that they detect light and dark. They do not detect images, however.
- Cnidarians are known as the “stingers” because of their special cells called cnidocysts. Cnidocysts line the tentacles that are characteristic of cnidarians. They are bell-shaped with a barb on the tip. When something brushes against the barb, it triggers the operculum (lid) on the top of the cell to open and the nematocyst to be ejected. The nematocyst is like a harpoon. Venom is pumped through a coil that links the nematocyst to the cnidocyst, through the nematocyst, and into the victim. This is what causes the sting.
- Cnidarians have an incomplete digestive system. Food enters and exits the same way (the mouth is also the anus).
- Much like plants, cnidarians display the alternation of generations life cycle with two stages: polyp and medusa. In the polyp stage, the tentacles are facing upwards while the bell is attached to a surface. Polyps reproduce asexually by budding, are non-motile, can make hundreds of medusa, and are filter feeders. Medusae reproduce sexually and are motile and predatory. Their reproductive organs are called gonads which produce eggs or sperm. To reproduce, they gather together and release their eggs and sperm.
- All animals in this phylum have radial symmetry.
- Predatory
- Live in fresh and saltwater (saltwater is more common)
Phylum Cnidaria lab
Analysis Questions
1. Cnidarians display the Alternation of Generations life cycle. There are two "generations": polyp and medusa. The polyp generation is non-motile and stuck to a surface. It filter feeds through feeding polyps and also produces medusa asexually through budding. The medusa generation is motile. They are predatory and have two different sexes, male and female. They reproduce sexually by releasing their eggs and sperm once they gather in the same area.
2. Cnidocytes is are the cells that line the tentacles of cnidarians. They contain the nematocyst within them. The nematocysts are ejected from the cnidocyte when the barb triggers the operculum to open and actually pierce into the victim.
3. The barb on the tip of the cnidocyte triggers the operculum to open. When that happens, the nematocyst is ejected and pierces into the victim. Venom is pumped through the coil that is attached to the nematocyst and into the victim.
4. There are two types of polyps: feeding and reproductive. The feeding polyp captures and digests food. The reproductive polyp produces medusae asexually through budding. The medusae reproduce sexually through eggs and sperm
5. Portuguese man-o-war:
1. Cnidarians display the Alternation of Generations life cycle. There are two "generations": polyp and medusa. The polyp generation is non-motile and stuck to a surface. It filter feeds through feeding polyps and also produces medusa asexually through budding. The medusa generation is motile. They are predatory and have two different sexes, male and female. They reproduce sexually by releasing their eggs and sperm once they gather in the same area.
2. Cnidocytes is are the cells that line the tentacles of cnidarians. They contain the nematocyst within them. The nematocysts are ejected from the cnidocyte when the barb triggers the operculum to open and actually pierce into the victim.
3. The barb on the tip of the cnidocyte triggers the operculum to open. When that happens, the nematocyst is ejected and pierces into the victim. Venom is pumped through the coil that is attached to the nematocyst and into the victim.
4. There are two types of polyps: feeding and reproductive. The feeding polyp captures and digests food. The reproductive polyp produces medusae asexually through budding. The medusae reproduce sexually through eggs and sperm
5. Portuguese man-o-war:
- Class Scyphozoa
- Medusa dominant
- Class Hydrozoa
- Polyp dominant
phylum platyhelminthes
Characteristics:
- These organisms have bilateral symmetry.
- They are triploblastic, meaning they have a true mesoderm in addition to their ectoderm and endoderm. The mesoderm makes up the muscles and remaining organ levels. Between the ectoderm and endoderm is solid mesoderm, so they are acoelomates, meaning they have no body cavity.
- Platy means flatty! These are the flatworms.
- There is an incomplete digestive system with a gastrovascular cavity and an excretory system made of "flame cells" and pores. Flame cells are located all along the organism near the skin, so the flatworms basically excrete wastes all over their bodies.
- They have a nerve ladder (which is a more organized way of sending messages around the body), a rudimentary "brain", eyespots (detect light and dark), and auricles (detect vibrations).
- These organisms mostly reproduce sexually, but can reproduce asexually. They have fantastic powers of regeneration, so if a flatworm is cut in half, both halves can regrow the missing half and continue to live.
- The sensory organs appear on the anterior. Cephalization begins in this phylum.
Class Turbellaria
- Includes planaria (a freshwater flatworm)
- eat dead and dying things on the bottom of a lake
- also includes many marine varieties
- includes the parasitic flukes
- liver, blood, lung, heart, and intestinal flukes
- many have intermediate hosts
- they do not have eyespots or a nerve ladder because they are highly specialized to their habitat
- liver, blood, lung, heart, and intestinal flukes
- flame cells
- classical endoparasite (tapeworms!)
- appears degenerative but is actually highly specialized to habitat
- human tapeworms can grow up to 20m long and live up to 30 years
Phylum platyhelminthes lab
Analysis Questions
1. The tapeworm is flat, so it folds over on itself to fit.
2. The hooks and suckers allow the tapeworm to attach onto the side of the intestine,
1. The tapeworm is flat, so it folds over on itself to fit.
2. The hooks and suckers allow the tapeworm to attach onto the side of the intestine,
3. Clonorchis
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Planaria
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4. Ectoderm: the skin and nervous system
Mesoderm: muscle and remaining organ levels
Endoderm: digestive system
5. Flatworms have bilateral symmetry, flame cells, a rudimentary “brain”, a nerve ladder nervous system, eyespots, auricles, and are triploblastic. This phylum is also where we start to see cephalization happening.
6. a) bilateral symmetry
b) non-segmented, acoelomates, triploblastic
c) gastrovascular cavity, mouth, flame cells
d) nerve ladder
7. a) having both male and female reproductive organs on the same organism; no different sexes
b) the nerves are arranged like a ladder; a more effective way of sending messages
c) excrete wastes; located near the skin all over the body
d) can be a form of asexual reproduction; if the organism is cut in half, both halves can regrow (regenerate) the missing half.
Mesoderm: muscle and remaining organ levels
Endoderm: digestive system
5. Flatworms have bilateral symmetry, flame cells, a rudimentary “brain”, a nerve ladder nervous system, eyespots, auricles, and are triploblastic. This phylum is also where we start to see cephalization happening.
6. a) bilateral symmetry
b) non-segmented, acoelomates, triploblastic
c) gastrovascular cavity, mouth, flame cells
d) nerve ladder
7. a) having both male and female reproductive organs on the same organism; no different sexes
b) the nerves are arranged like a ladder; a more effective way of sending messages
c) excrete wastes; located near the skin all over the body
d) can be a form of asexual reproduction; if the organism is cut in half, both halves can regrow (regenerate) the missing half.
8. Characteristics
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Endoparasite: Taena
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Free-Living: Planaria
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phylum Nemotoda
Characteristics:
- Complete digestive system with a mouth that is separate from the anus (tube within a tube body plan).
- Triploblastic and pseudocoelomate. The pseudocoelom is located between the mesoderm and endoderm.
- Lateral lines used for coordination of movement.
- Sexual reproduction; no regeneration.
- Roundworms
- Most are very tiny or microscopic.
phylum nemotoda lab
Analysis Question
- Vertically
- The main nervous cord.
- No, but they do have a rudimentary nervous system used for coordination of movement.
- It has no sense organs, only a digestive system and a reproductive system.
- The eggs are fertilized by sperm and ingested through unwashed fruits or vegetables. The embryo undergoes mitosis to grow into a full-sized worm. During the juvenile stage, the Ascaris worm may travel around the host’s body through the circulatory system. The worm usually ends up in the intestine where it feeds off of the host’s nutrients. The female worm makes eggs and lays them so they can be fertilized by male sperm.They usually live in humans. The eggs (fertilized and unfertilized) are excreted from the host’s digestive system back into the environment and the cycle is repeated.
- They can live in humans; they live mostly in the intestine but can travel through the circulatory system; they are both nematodes; the female is larger than the male.
- It gets between the toes of its intended host and causes them to itch. When the host scratches their toes, they create openings into the circulatory system where they enter. The hookworm travels through the circulatory system and passes through the heart where is crosses into the respiratory system via the lungs. The hookworm then causes the host to cough it up into their mouth where it is swallowed back down into the digestive system. It lives in the intestines.
8. Ascaris
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8. Trichina
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8. Necator
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9. By cooking pork thoroughly.
10. The mesoderm and endoderm
11. The reproductive organs; the ovoduct, ovaries, testis, etc.
12. The parasitic nematodes cause harm to other organisms, lack sensory organs and developed nervous systems while free-living nematodes have sensory organs and nervous systems and are essential to soil as they are decomposers.
13. Advantages
10. The mesoderm and endoderm
11. The reproductive organs; the ovoduct, ovaries, testis, etc.
12. The parasitic nematodes cause harm to other organisms, lack sensory organs and developed nervous systems while free-living nematodes have sensory organs and nervous systems and are essential to soil as they are decomposers.
13. Advantages
- doesn’t have to use energy to find food
- entirely reliant on another organism for survival; no host means they die
Characteristics
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Taena
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Clonorchis
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Ascaris
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Necator
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Trichina
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hydra lab
daphnia lab
planaria lab
This planarian's name is King Charles "Fatty the Platy" Macbeth