Smaller Ecdysozoans

Pseudocoelomates

Nematoda are: Pseudocoelomates or Coelomates

Nematoda

Which is the largest pseudocoelomate phylum?

Nematoda- General Characteristics

 

• Marine & freshwater (benthic in algal mats, sediments, etc.),

• parasitic

• Terrestrial in water films

• Ubiquitous

• Very high densities: 4,420,000/m2 (off Dutch coast)

Carnivores, small metazoans

What are the free-living Nematodes nutrition and what do they eat?

Nematodes- Deposit feeders

• Diatoms, algae, fungi, bacteria

• Terrestrial suck nutrients from roots of plants

Free-living and Parasitic

Nematodes are mostly what?

Ascaris

• Nematode (Parasitic

• prevalent in southeast US, children especially

•  eggs viable up to 10 years

Trichinella

• Nematode (Parasitic)

•  largest intracellular parasite

•  adults live in intestinal walls

• juveniles carried in blood stream to striated muscle

  •  form calcified cysts in muscle cell (pain and stiffness)

  •  cell molecularly reprogrammed to become ‘nurse cell’

  •  loses contractile capability and nourishes larva

•  transferred by eating undercooked meat

Wuchereria bancrofti

• Nematode (Parasitic)

• Cause of elephantiasis

• Transmitted by mosquito bites

• Adults live in lymph system (block it)

Loa loa, the African eye worm

• Nematode (Parasitic)

• Lives in subcutaneous tissue of humans and baboons

Beneficial Nematodes

• They attack insect, eat it from the inside out and control them.

• It kills the insect and reproduce offspring inside them.

• Control insect population

Bad Nematodes

• Destroy crops

• Attack plants roots and kills them

Phylum Nematorpha

• Horse hair

• Affects crickets. Makes them to seek out water and when the cricket is in the water and exit from them.

• Not sure if affects the crickets brain.

Rotifera

Who is Cryptobiosis?

Cryptobiosis

• Get away and shrivel the liquid of their body

• Survive 2-4 years

Major Characteristics of the Rotifera

• Most are freshwater, but are some marine

• Commonly more than 1000 per liter of water

• Most 0.1-1 mm in length

• Total of about 1000 cells

• Eutelic

• Body generally transparent

Rotifera

• Dominate freshwater zooplankton

• Important in nutrient recycling

• Most free-living, motile, but some sessile and a few colonial or parasitic

  • Parasitic are both endo- and epiparasites

Phylum Rotifera

Who eats zooplankton?

Rotifer morphological plasticity

• Seasonal change: cyclomorphosis

• Predator-induced change (chemical cues)

• Asplancha

• Brachionus grow protective spines – in next generation

Eutely

• One of the emerging patterns

• Is when your growing, your cells divide normally. But when you become adult, it does not increase the number (fixed number of cells through its life).

Major Characteristics of the Tardigrada

• Most very small (0.3-0.5 mm)

• Live interstitially in shallow and deep water, water films around terrestrial objects (similar to rotifers)

• Molt cuticle

• Eggs deposited in molted cuticle

• Eutelic

External Morphology of the Tardigrada

• Short, plump, cylindrical body

• 4 pairs of ventral stubby legs that terminate in claws