Nematoda and Echinoderms

Question 1

Nematode Phyllum

Answer 1

• Roundworms (25,000+ species)
• Bilateral symmetry, cylindrical tapering body, pseudocoelomates
• Have a thick external coat (cuticle), which sheds
• Multi-layered cuticle maintains internal high pressure
• Muscles not antognostic and uses hydrostatic skeleton to pull them into shape

Question 2

Free living Nematodes

Answer 2

• Marine, freshwater or terrestrail
• Found in all habitats
• 90% of animals on seabed
• Important in soil-nutrient cycling
• Nematodes are responsible for the loss of 12% of global crops as some species are pests

Question 3

Parasites

Answer 3

• Virtually all animal and plant groups have parasites
• Elephantiasis, cuased by infection with filariasis type nematodes which infects lymphatic system, causing swelling

Question 4

Echinoderms

Answer 4

• “Echino” = spiny, “derma” = skin
• Sea lilies, sea urchins, starfish and sea cucumbers
• All marine organisms
• Larvae are bilateral, but adults have a 5-fold radial symmetry
• Thin epidermis covering a endoskeleton (Calcarous places) ad external spines
• Water vasular system, internal canals and external tube “feet”