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What is the primary unifying characteristic of Ecdysozoans?
ecdysis (molting)
Characterize the structure and function of a cuticle.
collagen cuticle; protection and support
What type of body plan do nematodes have?
Pseudocoelom- cavity incompletely lined by mesoderm
Describe the variety of nematode habitats.
marine, FW, soil- nutrient cycling/decomposition; parasites of animal and plant tissues
Comment on size range of nematodes.
microscopic to several meters
What is the function of the pseudocoelom?
hydrostatic skeleton; distributes nutrients and gases bc there's no circulatory/gas exchange systems
How do nematode muscles compare with annelid muscle types?
Nematodes- longitudinal muscles
Annelids- circular muscles that constrict the body wall
What's the difference between dioecious and sexual dimorphism?
dioecious- seperate sexes
dimorphism- sexes looks different
How are Ascaris worms transmitted from one host to the next host? What are the stages of Ascaris life cycle? Where are adult Ascaris worms located in the human body?
Transmitted in:
- Feces
- Contaminated Vegetables
- Hygiene
Life Cycle:
1. Eggs are ingested and people defecate. (Fertilized eggs are viable in fecal matter and go through cellular division and form the larvae, which is then eaten.)
2. Acaris goes to digestive tract, then circulatory system, and straight into lungs.
3. It gets coughed up, then stays in the Intestinal Tract
Adults located in intestine.
Are Ascaris worms sexually dimorphic?
Yes, the females are larger than the males
What is the geographic distribution of Ascaris worms?
Warm, humid regions; estimated 25% of the world's population infected
How do hookworms enter their host? How do they migrate through the host? What are the stages of a hookworm life cycle?
Worms penetrate skin (usually between toes; walking barefoot) using cutting plates
Can migrate subcutaneously (just below skin) and eventually attach to intestine causing severe anemia
What worms cause trichinosis? What are the different hosts for these worms?
Trichinella worms; Juveniles encyst in skeletal muscle of mammals
How are humans infected with Trichinella?
eating improperly cooked meat
What type of cell is transformed into a “nurse cell” by Trichinella? What is the function of a “nurse cell”?
juveniles convert infected host cell into "nurse cell"
Textbook: Juveniles cause astonishing redirection of gene expression in their host cell, which loses its striations and becomes a nurse cell that nourishes the worm
What is the most common human nematode parasite in the US? How is it transmitted to humans?
Pinworm (mainly infects children)
Adult worms inhabit lower region of colon
Females migrate to perianal region at night and lay eggs
Transmitted hand to mouth (poor hygiene)
Where do adult pinworms reside in humans?
lower region of colon
What are some diseases caused by nematode filarial worms? What are the vectors for the diseases?
Elephantiasis- Wuchereria bancrofti; vectored by mosquitos
Heartworm disease- transmitted by mosquitos
River Blindness- Loa loa worm “eye worm”; vectored by biting flies (Chrysops)
Dracunculiasis- Guinea worm disease; ingested in drinking water contaminated with fleas containing larvae
What are the stages of the life cycle of Wuchereria bancrofti? Where do adult Wuchereria bancrofti reside in humans?
Wuchereria bancrofti block vessels of lymphatic system -> causes scarring and extreme swelling (elephantiasis), vectored by mosquitos
What are the hosts for Nematomorpha juveniles? Briefly describe their life cycle. What type of environment do nematomorph adults inhabit?
Free-living adults; larvae are parasitic on arthropods
Ex. parasitic on crickets, control cricket body to find bodies of water and complete life cycle
What three phyla are included in Clade Panarthropoda?
Arthropoda, Onychophora, and Tardigrada
What is a hemocoel?
Lined by ECM (rather than by mesoderm in a coelom), contains blood
Unifying characteristic of Clade Panarthropoda
Describe the appearance of Onychophorans (velvet worms) including types of appendages and cuticle structure. What type of adaptation do they have for feeding/defense? What type of gas exchange system is found in "velvet worms"? What is their typical habitat?
Appearance/habitat: "claw bearing"; Tropical caterpillar-like, nocturnal predators
Appendages and cuticle structure: Thin, flexible cuticle (protein and chitin), shed in patches; covered w/ tubercles (with colored scales/sensory bristles); paired, unjointed legs; one-pair antennae
Feeding/defense: mandibles; slime glands (sticky adhesive secretions to capture prey)
Gas exchange: tracheal system
Other: ladder-like nervous system; open circulatory system; 1 pr nephridia per segment (uric acid)
Describe tardigrades including appendages and cuticle structure. What adaptation do they have for feeding? In what environments do tardigrades reside?
Appendages: minute, unsegmented; long oval body; 4 pairs of stubby/fleshy/unjointed legs with claws
Cuticle: shed non-chitinous cuticle
Feeding: "piercing" stylet to feed on animal/plant tissues
Environment: terrestrial; live in water films on mosses, lichens, soils
Other: lack circ./resp. systems; Malpighian tubules (excretion of nitrogenous waste)
What mechanism do tardigrades use for surviving harsh environmental conditions?
Cryptobiosis- can survive harsh environmental conditions in dehydrated state, "Tun"
- Produce TDPs (Tardigrade-specific intrinsically Disordered Proteins that become rigid/glassy when desiccated)
- 0.1% of normal metabolism
