High Desert Vapes Friday Night Free E-Liquids Giveaway!!
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I am studying for a zoology exam~
I'mma teach you people about some ecdysozoans. hold on to your butts~
I'mma teach you people about some ecdysozoans. hold on to your butts~
Protostomia includes the sister clases lophotrochozoa and ecdysozoa.
Ecdysozoea - body covered by a non-living layer called a cuticle which much be shed in order for the animal to grow.
Ecdysis = shedding of cuticle.
Ecdysozoea - body covered by a non-living layer called a cuticle which much be shed in order for the animal to grow.
Ecdysis = shedding of cuticle.
chapter 12 - smaller ecdysozoans
phylum nematoda - round worms. 25,000 species described - underestimated. probably up to a million awaiting description. VERY abundant, ~80% of all individual animal on earth are nematodes. a square meter of soil or ocean bottom can contain a million of them. inhabit virtually all environments, worldwide distribution. approximately half of all described species are parasites of plants & animals. Most species are <5cm long. pseudocoelom - fluid filled under high pressure.
have amphids, chemosensory organs, at anterior (shared/derived)
the cuicle is made mostly of collagen, secreted by epidermis (hypodermis)
Longitudinal muscles ONLY, no circular. No muscles in gut wall.
High fluid pressure snaps worm back straight after muscle contraction, moves with a violent thrashing motion for locomotion and also to move food through the gut.
phylum nematoda - round worms. 25,000 species described - underestimated. probably up to a million awaiting description. VERY abundant, ~80% of all individual animal on earth are nematodes. a square meter of soil or ocean bottom can contain a million of them. inhabit virtually all environments, worldwide distribution. approximately half of all described species are parasites of plants & animals. Most species are <5cm long. pseudocoelom - fluid filled under high pressure.
have amphids, chemosensory organs, at anterior (shared/derived)
the cuicle is made mostly of collagen, secreted by epidermis (hypodermis)
Longitudinal muscles ONLY, no circular. No muscles in gut wall.
High fluid pressure snaps worm back straight after muscle contraction, moves with a violent thrashing motion for locomotion and also to move food through the gut.
No circulatory system or respiratory system - large surface area. directly absorbs oxygen from environment. Many parasitic species don't even require oxygen for metabolism; generates energy anaerobically. The saved space is filled up with reproductive organs. typically sexual reproduction - separate sexes. Internal fertilization. Sexual dimorphism. Sperm are not flagellated - amoeboid sperm cells. jesus christ how horrifying. unique to nematodes, perhaps because typical sperm can't swim against high pressure of body fluid. males also have "spurs" to open female genitalia. can produce eggs prolifically.
PARASITIC ROUNDWORMS:
1) pinworms. most common parasite in US. 30% of children and 16% of adults will be infected. Adult pin worms are ~1cm long. Live in large intestine of human. Mating occurs, gravid females move to anus at night to lay eggs, which causes itching. So then you scratch your .... (naturally) which dislodges eggs into clothing or bedding, or lodges them under fingernails, which will then eventually be put in your mouth and ingested. Spread from hands amongst kids. They do not really cause any health problems, they're just annoying.
1) pinworms. most common parasite in US. 30% of children and 16% of adults will be infected. Adult pin worms are ~1cm long. Live in large intestine of human. Mating occurs, gravid females move to anus at night to lay eggs, which causes itching. So then you scratch your .... (naturally) which dislodges eggs into clothing or bedding, or lodges them under fingernails, which will then eventually be put in your mouth and ingested. Spread from hands amongst kids. They do not really cause any health problems, they're just annoying.
2) Large intestinal roundworms - Ascaris. Much more prevalent worldwide, over 1 billion people infected. Also animal hosts, not just humans. Adults live in small intestine, absorbing nutrients. Eggs are excreted in feces, on ground someplace. Humans then have to inhest them. So again, children in the sandbox, or raw vegetables, shelled eggs are ingested. Eggs hatch in digestive tract, burrow through intestines & enter blood vessel. Catch a ride to the lungs, exit blood & hang out in Alvioli. Then they migrate up the respiratory tract to the pharnyx, where they are then swallowed. Which means they just went on a field trip to wind up where they were to begin with, stupid worms.
Causes malnutrition - or in large numbers, can block intestine entirely.
Or, in the course of their wanderings can wind up in another organ... such as your brain.
Causes malnutrition - or in large numbers, can block intestine entirely.
Or, in the course of their wanderings can wind up in another organ... such as your brain.
3) Hookworms. Adults live in small intestines. Doesn't just feed on nutrients, but attaches & feeds on blood. Causes anemia and exhaustion. Again excreted in feces, hatch on ground & juveniles feed on organic matter in soil until a barefoot human wanders along. Then it burrows through the skin and enters blood stream. Then to lungs, throat, gulp, like the Ascaris.
Most prevalent in the southeast US
Most prevalent in the southeast US
4) Trichina worms. Trichinalla genus. Causes trichinosis. Usually caused by contaminated, undercooked meat. Lives in skeletal muscles. Associated with undercooked pork in the past. Now wild game is the primary cause - Boar, Bear, Raccoon.
( who the hell eats raccoon, seriously? i wouldn't eat a career scavenger. Wouldn't eat a raccoon any more than I would want to eat a vulture. )
( who the hell eats raccoon, seriously? i wouldn't eat a career scavenger. Wouldn't eat a raccoon any more than I would want to eat a vulture. )
5) Filarial worms. Live in the circulatory system of hosts. Important parasites of humans, live in lymphatic system, transmitted by mosquitoes. Causes Elephantiasis. Blocks lymphatic vessels - swollen lower extremities. Lymphatic system returns plasma lost at capillaries to the heart. Low pressure system anyway, between gravity and blockage it's retained. Mosquitoes uptake juvenile worms and transmits to another hosts. Juveniles travel through circulatory system. 120 million people infected worldwide, mostly in africa & asia. 40 million people disfigured & incapacitated.
Most common Filarial worm in the US is the dog heartworm. Adults live in heart, juveniles circulated through blood. also transmitted by mosquitoes. prevalent in south east USA. half of dogs are at risk. Blocks blood flow.
Most common Filarial worm in the US is the dog heartworm. Adults live in heart, juveniles circulated through blood. also transmitted by mosquitoes. prevalent in south east USA. half of dogs are at risk. Blocks blood flow.
Phylum Nematomorpha - "Nematode form"
Smaller group, 351 species known. common name horsehair or gordian worms. adults are free living, primarily found in moist terrestrial & freshwater (only 3 marine species). The juveniles are parasites of arthropods (insects, spiders, crabs). up to a meter long but much thinner than roundworms. Longitudinal muscles only. because they're so long & skinny they often get tangled in knots. Have a mouth but gut is non-functional, pharynx plugged, though they still have a remnant. No circulatory or respiratory systems. Adults only emerge from horse when it's in or near water. Late in development they do SOMETHING to cause the host to seek water & jump in, often drowning insect.
(zombie bugs omg omg omg)
Once considered to be nematodes but split into own clade.
Nematoda and nematomorpha collectively called Nematoidea.
Smaller group, 351 species known. common name horsehair or gordian worms. adults are free living, primarily found in moist terrestrial & freshwater (only 3 marine species). The juveniles are parasites of arthropods (insects, spiders, crabs). up to a meter long but much thinner than roundworms. Longitudinal muscles only. because they're so long & skinny they often get tangled in knots. Have a mouth but gut is non-functional, pharynx plugged, though they still have a remnant. No circulatory or respiratory systems. Adults only emerge from horse when it's in or near water. Late in development they do SOMETHING to cause the host to seek water & jump in, often drowning insect.
(zombie bugs omg omg omg)
Once considered to be nematodes but split into own clade.
Nematoda and nematomorpha collectively called Nematoidea.
Phylum Kinorhyncha - "Mud Dragons" 179 known species, all marine. <1mm long. live in muds & sediments. Feed on organic matter - algae & bacteria.
head surrounded by hairs called "scalids" extended on neck. Body has 11 segments, also hairy.
head surrounded by hairs called "scalids" extended on neck. Body has 11 segments, also hairy.
Phylum Loricifera - 30 marine species. <1mm long. lives attached to marine gravel. not discovered until 1983. Part of the meiofauna - animals that live in the spaces between sand, mud, & gravel grains.
Extentable, hairy mouth that is retracted back into shell-like lorica.
Extentable, hairy mouth that is retracted back into shell-like lorica.
phylum priapulida - 19 marine species. up to 15cm long. live in bottom & borrow with just interovert (head) stucking out. predatory. also have scalids around the mouth. trunk wrinkled, but not really segmented. lives in cool water, northern temperate.
common name "penis worm". eaten in japan, naturally.
common name "penis worm". eaten in japan, naturally.
CLADE PANARTHROPODA.
3 phyla:
Tardigrada 1,157 species
onychophora 182 species
Arthropoda 1,235,858 species
more species of arthropods than every other type of life combined.
Shared Derived:
-Hemocoel. Body cavity in which blood circulates.
-Paired appendages, most end in hooks or claws at the tips.
3 phyla:
Tardigrada 1,157 species
onychophora 182 species
Arthropoda 1,235,858 species
more species of arthropods than every other type of life combined.
Shared Derived:
-Hemocoel. Body cavity in which blood circulates.
-Paired appendages, most end in hooks or claws at the tips.
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