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Questions and Answers
Which of the following phyla is known for its members commonly referred to as 'water bears'?
Which of the following phyla is known for its members commonly referred to as 'water bears'?
Which ecological niche category contains phyla that are found in all environments, including sea, freshwater, land, and air?
Which ecological niche category contains phyla that are found in all environments, including sea, freshwater, land, and air?
Which phylum is characterized by a body plan that allows for ecdysis, shedding their outer layer?
Which phylum is characterized by a body plan that allows for ecdysis, shedding their outer layer?
Which of the following phyla has the least representation in terms of individual counts, as indicated by the provided data?
Which of the following phyla has the least representation in terms of individual counts, as indicated by the provided data?
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Which of these phyla is most diverse in its ecological adaptations, as indicated by the ability of its members to occupy various ecological niches?
Which of these phyla is most diverse in its ecological adaptations, as indicated by the ability of its members to occupy various ecological niches?
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Which of the following phyla do not possess an exoskeleton that undergoes ecdysis?
Which of the following phyla do not possess an exoskeleton that undergoes ecdysis?
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What is the primary characteristic of the phylum Chaetognatha?
What is the primary characteristic of the phylum Chaetognatha?
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Which of the following statements about the diversity of phyla is true?
Which of the following statements about the diversity of phyla is true?
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Which of the following groups has the highest known abundance based on the provided data?
Which of the following groups has the highest known abundance based on the provided data?
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What ecological niche do Priapula and Loricifera typically occupy?
What ecological niche do Priapula and Loricifera typically occupy?
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Study Notes
Medical Zoology: Protists and Invertebrates
- Protists, flatworms, roundworms, arthropods (including mosquitoes) are of medical importance due to their direct impact on human health, either as pathogens or disease vectors.
Arthropods
- Arthropods are a diverse group with high species richness.
- They have segmented bodies, jointed legs, and an exoskeleton.
- The exoskeleton is shed periodically for growth.
- They are divided into groups known as tagmata.
- Examples include:
- Introduction to Arthropoda
- Phobias (related to insects)
- Venoms and allergens
- Blistering and urticating arthropods
- Blood-sucking insects
- Arthropods as vectors of other organisms
- Insects, as vectors of disease
Insect Nuisances and Phobias
- High densities of some species can be a nuisance (e.g., ants, silverfish)
- Filth-frequenting insects are a nuisance (e.g., cockroaches, blowflies)
- Biters and stingers (e.g., ants, bees, wasps) can also be a problem.
- Phobias and anxiety about insects can be a concern
- Entemophobia: fear of insects
- Arachnophobia: fear of spiders.
Stinging Insects (Hymenoptera)
- Bees, wasps, and ants are stinging insects.
- They often sting in nest defense or predation.
- Social insects can cooperate to sting intruders, escalating the impact.
- Honeybee stings have backward-pointing barbs making them single use; the bees die after stinging.
- Wasp and ant stings are unbarbed, capable of repeated use.
- Venom constituents include low molecular weight substances, such as biogenic amines, phospholipids, and peptides.
- Formicine ants spray formic acid.
- Normal local reactions include itch, swelling, and pain.
- Systemic allergic reactions can be observed (mild to severe).
Flightless Blood-Suckers
- Cimex lectularius and C. hemipterus (bed bugs) belong to the order Hemiptera.
- These are hidden pests and tend to feed at night, causing itch and lesions.
- Cimex can survive many days without eating.
- Fleas (Siphonaptera) are insects with human hosts for their primary source of food.
- Some fleas like Xenopsylla cheopis are vectors for the plague.
- Chigoe fleas (Tunga penetrans) live beneath the skin.
- Human lice (Psocodea) can transmit diseases.
- Scabies mites (Sarcoptes scabiei) burrow into the skin, causing itching, rash, secondary infections, and a physical contact transmission.
- Physical contact is the means of transmission for the scabies mite.
Winged Blood-Suckers
- Various flying insects feed on human blood (e.g., kissing bugs, mosquitoes).
- Mosquitoes transmit diseases like malaria, sleeping sickness, Chagas disease, yellow fever, dengue, and leishmaniasis.
- Ticks also can carry diseases such as typhus and Rocky Mountain spotted fever.
- Tsetse flies transmit African trypanosomiasis.
- Insects can act as vectors of disease for various viruses, protists, and nematodes.
Vectors
- Insects can transmit viruses, protists, and nematodes causing human diseases.
- Examples of diseases transmitted by insects include dengue fever, yellow fever, typhus, plague, malaria, and sleeping sickness.
Pathogens
- Viral, bacterial, protists and nematode worms are common pathogens
- Bacterial pathogens include Rickettsia prowazekii (epidemic typhus).
- Parasites such as vectors cause diverse and complex diseases; most transmission is when the pathogen replicates in the insect vector.
Arboviruses
- Arboviruses (arthropod-borne viruses) are viruses that replicate in both invertebrate and vertebrate hosts.
- Some examples of arboviruses include yellow fever, dengue, Japanese encephalitis, and equine encephalitis. These viruses are transmitted by various blood-feeding insects, often mosquitoes.
Epidemic Typhus
- Caused by Rickettsia prowazekii.
- Transmitted by human body lice (Pediculus humanus).
- The bacteria multiply in the lice, are voided in the feces, and transmitted by scratching.
The Plague
- Caused by Yersinia pestis.
- Transmitted by fleas.
- Has sylvatic (wild animal) and urban (rat) cycles.
- Bubonic and pneumonic are two forms of plague with varying outcomes.
Disease Reservoirs
- Non-human hosts act as reservoirs of disease within sylvatic cycles .
- Human encroachment into the wildlife habitats often brings humans into contact with vectors and reservoirs for various diseases.
- These events may complicate effective disease control.
Additional Reading
- There are additional readings on various organisms, their descriptions, and their impact on human health.
Limulus Amebocyte Lysate (LAL)
- LAL test is a blood-clotting assay from horseshoe crabs.
- Used to detect bacterial endotoxins.
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Description
Test your knowledge on the medical significance of protists and invertebrates, particularly arthropods. This quiz covers their roles as pathogens and disease vectors, along with their biological characteristics. Dive into the fascinating world of these organisms that impact human health.