Phylum Nematoda Flashcards
The 2 major kinds of body cavities
Pseudocoelom
True coelom
Pseudocoelomate characteristics
Body wall lined with mesodermal tissue
Intestine has no mesodermal tissue
Eucoelomate characteristics
Layers of mesoderm on inside of body wall and outside digestive tract
Have muscle layers in both places
Much better developed digestive system
Roundworm characteristics
Mostly free living
Notable for lack of size variation
Cylindrical and unsegmented
Most abundant pseudocoelomate
Occur in virtually all habitats
Ecological importance
Aerate soil
Recycle nutrients
Decompose toxins and wastes
Body organization
Elongated
Wormlike body
Tube within tube design
Pseudocoelom
Triploblastic
Body wall
Has syncytial epidermis
Adhesive glands usually present
Flexible cuticle
Movement
Have only longitudinal muscle
Feeding & Digestion
Eat living cells
Some predatory carnivores
Some phytophagous
Complete digestive tract
Muscular pharynx
Nervous system
Ganglia around pharynx
Dorsal and ventral nerve cords
Senses
Chemoreceptors sometimes in head or tail
Excretion
Renette cells
Excretory pore
No circulatory or respiratory system
Reproduction
Sexual dimorphism
Internal fertilization
Direct development
No larval stage
4 juvenile stages but resemble adult
Cryptobiosis
Ecological effects of nematodes
Fundamental in recycling nutrients in all ecosystems
Help to decompose toxins
Human impacts of nematodes
Cause extensive crop damage
