Chapter 18: Smaller Ecdysozoans

ecdysozoans are animals with

molting cutical

phylum nematoda common name

roundworms

phylum nematoda habitat

everywhere/topsoil

phylum nematoda life

parasitic

phylum nematoda model organism

caenorhabdities elegans

phylum nematoda cells

eutely (fixed number of somatic cells)

phylum nematoda movement

via longitudinal muscles only
no motile cilia/flagella

phylum nematoda excretory system

glands empty into a pore
no protonephridia

phylum nematoda thick, collagen cuticle function

protects from desiccation
maintains pressure

phylum nematoda digestive tract

mouth, muscular pharynx, intestine, rectum, anus

phylum nematoda intestine thickness

one cell layer

phylum nematoda defecation

pull anus open > hydrostatic pressure forces waste out

phylum nematoda metabolism type

anaerobic/obligate aerobes

phylum nematoda nervous system structures

nerve ring, dorsal/ventral cords, sensory papillae, amphids (phasmid in parasites)

phylum nematoda fertilization

internal

phylum nematoda males have ___ for reproduction

pair of copulatory spicues

phylum nematoda eggs

stored in uterus until deposition

phylum nematoda number of juvenile stages

four; separated by cuticle molt

ascaris lumbricoides

intestinal parasite from uncooked vegetables/unwashed hands

ascaris lumbricoides life cycle

swallow egg > intestinal wall > lungs > trachea > stomach > mature in intestine

hookworms

bloodsuckers; growth issues/allergies

hookworms life cycle

egg in feces > hatch in soil > live on bacteria > burrow into skin > lungs > digestive tract

trichina worms

trichinosis; undercooked meat

trichina worms lifecycle

adult releases juvenile in intestine > penetrate blood

filarial worms

elephantiasis, river blindness, dog heartworm

phylum nematomorpha common name

horsehair worms

phylum nematomorpha roots

nema (thread) and morpha (form)

phylum nematomorpha ____ juveniles and ____ adults

parasitic in arthropods, free living

phylum nematomorpha posterior end

2-3 caudal lobes

phylum nematomorpha lack what systems

circulatory, respiratory, excretory

phylum nematomorpha nerve cord

midventral

phylum nematomorpha eggs

released in long strings in water

phylum kinorhyncha common name

mud dragons

phylum kinorhyncha roots

kinein (to move) and rhynchos (beak)

phylum kinorhyncha body structure

head, neck, trunk (11 segments)

phylum kinorhyncha spines

scalids for locomotion/sensory

phylum kinorhyncha movement

burrows in mud, anchors with spines

phylum kinorhyncha mouth

a tip proboscis

phylum kinorhyncha nervous system

in contact with epiderms; multilobed brain

phylum kinorhyncha excretory system

solenocyte protonephridium

phylum kinorhyncha development

six juvenile stages, non molting adult

phylum priapulida common name

penis worms

phylum priapulida roots

priapos (phallus)

phylum priapulida life

burrowing and predaceous

phylum priapulida body

cylindrical up to 40 cm

phylum priapulida body divided into

introvert, trunk, caudal appendages

introvert with papillae and scalids for feeding

phylum priapulida

phylum priapulida non-metameric trunk covered in

tubercles and spines

phylum priapulida nerve cord

midventral

phylum priapulida fertilization

external

phylum priapulida development

direct/brooding

phylum loricifera roots

lorica (corset) and phora (bearing)

phylum loricifera habitat

marine gravel

phylum loricifera body structure

mouth cone, head, neck, thorax, abdomen

phylum loricifera lorica

rigid case for protection

phylum loricifera locomotion and sensing

9 scalids on introvert

phylum loricifera larval phase

higgins larvae

clade panarthropoda include

arthropods, onychophora, tardigrada

clade panarthropoda body cavity

hemocoel

hemocoel formation

fusion of blastocoel and coelom

clade panarthropoda hemocoel lined by

extracellular matrix

phylum onychophora common name

velvet/walking worms

phylum onychophora roots

onyx (claw) and pherein (to bear)

phylum onychophora habitat

moist environments

phylum onychophora body

cylindrical with paired appendages

phylum onychophora segmentation

no external

phylum onychophora skin

soft velvet made of protein and chitin

phylum onychophora cuticle

non hardened

phylum onychophora ___ and ___ on the body

tubercles, sensory bristles

phylum onychophora antennae

one large pair

phylum onychophora mouth

ventral with mandibles and slime secreting papillae

phylum onychophora legs

14-34 pairs of unjointed, stubby, clawed legs

phylum onychophora body wall

muscular

phylum onychophora ___ in each leg segment

nephridia

phylum onychophora ___ system with ____

tracheal with open spiracles

phylum onychophora nervous system

ladder-like with ventral nerve cords

phylum onychophora behavior

social and group hunting

phylum onychophora sensory

developed eyes, taste spines, and tactile papillae

phylum onychophora development

young leave mothers body

phylum tardigrada common name

water bears

phylum tardigrada roots

tardus (slow) and gradus (step)

phylum tardigrada body structure

unsegmented with four pairs of unjointed legs

phylum tardigrada cuticle

nonchitinous, molted at least 4 times

phylum tardigrada feeding

stylets: pierce cells and suck out contents
mouth: buccal tube to muscular pharynx

phylum tardigrada fertilization

seminal receptacle, cuticle piercing, deposit in objects/molted cuticle, male collects old cuticle

phylum tardigrada excretion

three excretory glands at intestine and rectum and empty into digestive tubes

phylum tardigrada movement

no circulatory muscles
cannot swim
crawl awkwardly

phylum tardigrada unique feature

suspended animation/cryptobiosis

suspended animation/cryptobiosis

ability to survive extreme conditions

phylum nematoda species count

25,000

phylum nematomorpha species count

320

phylum kinorhyncha species count

180

phylum loricifera species count

<100

phylum onychophora species count

70

phylum tardigrada species count

900