Phylum Nematomorpha - Jan.ucc.nau.edu

Blastocoelomates, 

Continued 

Phylum 

Loricifera 

General Characteristics: 

b. N species unknown, 

now about 35-40. 

2. Bilaterally, radially 

symmetrial, unsegmented, 

apparently 

psuedocoelomate. 

Locomotion: 

e. Appear to propel 

themselves along with 

spines and toes. 


Loricifera 


1. A recently discovered 

phylum (Kristensen 1983) 

from shell-gravel 

sediments. 

a. Now know to occur at 

great depth. 

Body Form: 

a. Extremely tiny, 1/4 

mm long. 

b. Head, neck, and thorax 

retractable into abdomen. 

1. Spines encircle coneshaped 

mouth. 

c. All surrounded by 

cuticle - lorica ("corsetbearers"). 

d. complete gut, diet? 

Reproduction: 

a. Poorly known like rest 

of group. 

b. Sexes separate, 

sexually dimorphic in 

head scales. 

c. unique "Higgins-larva" 

named after codiscoverer. 

1. originally thought to be 

a larval priapulan.


Priapula 


1. Named after the Greek 

god Priapos, although 

actual name-sake reported 

by B&B to be from 

Linnaeus (Priapus 

humanus) - human penis. 

Body Form: 

a. Bilaterally 

symmetrical, superficially 

annulated. 

b. Armed anterior end 

(introvert) that is 

retractable. 

1. Burrowing forms, 

structure assists in food 

capture. 

Body Form: 

c. Radially arranged 

nervous system located 

near surface of body 

d. Complete gut - often 

with diverticulae. 

e. Numerous 

protonephridia associated 

with the reproductive 

tract. 


Priapula 

Priapus humanus 

a. Reported to be 20 cm 

long (>9 inches!) 

b. Anterior end armed 

with spikes. 

Feeding: 

a. Extend introvert, hook prey, contract 

muscles and draw prey in. 

1. Amounts to a true urogenital system - 

observed in more derived forms. 

2. May assist habitation of sediments in hypoand 

hypersaline environments.

Body Form: 

f. Unique (apparently) respiratory structure 

- caudal appendage. 

1. No apparent effect if removed, however. 

With 

Pseudocoels? 

1. Cuticle, periodially 

shed (Ecdysozoa). 

2. Fluid filled body 

cavity, movement 

assisted by hydrostatic 

pressure. 

3. lorica-encased larva 

- very similar to 

Loriciferans. 

Reproduction: 

a. Gonochoristic, but 

copulation doesn't occur – 

spawning instead. 

b. Males first, female 

second - interesting, this 

is unusual for external 

fertilizers. 

Phylogenetic 

Position: 

3. Unusual groupdifficult 

to place due to 

affinities to pseudocoels 

and eucoels. 

With Eucoels? 

1. Body wall is lined - but 

lining does not cover 

internal organs. 

2. Yet extensions do 

support viscera. 

3. Overall, difficult to 

classify. 

Development: 

c. Is unusual for 

pseudocoels: radial 

holoblastic cleavage. 

d. Produces loricate 

larva.


Nematomorpha 

General Characteristics 

1. Wierd, once thought to 

represent spontaneous 

generation. 

a. Adults occur in horse 

troughs. 

b. attempts to revitalize 

horsehairs failed. 

Phylum Nematomorpha 

General 

Characteristics: 

2. Longitudinal 

muscles. 

3. No ciliated 

structures. 




2. Fairly abundant - 230 

spp 

3. Body form 

a. Similar to nematodes 

1. thick cuticle must be 

molted. 



Dissimilar to Nematodes. 

1. Do not show 

consistency in cell 

number (eutely). 

2. Pseudocoel filled with 

mesenchyme. 

3. Rudimentary digestive 

system. 



Dissimilar to Nematodes. 

a. nutrients absorbed from 

body of insect host. 

3. No excretory system 

4. No specialized genital 

system - cloacas in both 

sexes.



Reproduction - 

a. Example: Gordius 

after the Gordian Knot. 

1. intricate knot tied by 

King Gordius of Phrygia 

a. whoever untied it 

would be King of Asia. 



Life Cycle: 

a. Adults develop in 

bodies of insects. 

1. Cause them to seek 

water, once entering, they 

explode. 

2. Separate sexes mate in 

water. 



Life Cycle: 

4. Larvae ingested by 

host- when insects feed or 

drink near water. 

a. Use hooked proboscis 

to imbed in tissues 

Phylum Nematomorpha 

b. Alexander cut it with his sword and 

became King of Phrygia 



Life Cycle: 

a. Females lay eggs that 

wrap around aquatic 

vegetation. 

3. Eggs hatch, larvae 

remain free living for 

only a few days. 



Life Cycle: 

b. If unsuitable host 

ingests, will encyst and 

wait for intermediate host 

to be ingested by suitable 

host. 

1. Beetle -> mantid



2. Can also inhabit 

annelids, molluscs, 

crustceans, humans 

5. Mature worm develops 

beneath skin. 


Entoprocta 


b. Derivation of "entoproct" 

-anus within ring 

of tentacles. 

c. Kamptozoa - derived 

from flexible calyx that 

permits 

zoids to "nod." 

Phylum Entoprocta 

Cilia draw water from beneath tentacles. 

a. Food swept to mouth, anus within ring of tentacles. 


Entoprocta 

(Kamptozoa) 


1. Usually colonial 

organisms with upright 

zooids. 

a. ciliated tentacles 

surrounding the mouth 

and anus. 


2. Appear related to other similar groups: 

a. Bryozoans - ectoprocts 

b. but similarity is ecological rather than 

evolutionary. 


Entoprocta 

Reproduction 

a. Capable of 

reproduction by budding - 

hence colonial structure. 

b. Also sexual 

reproduction.


1. Sperm released into water; internal fertilization. 

3. Ciliated larva that is similar to that of annelids and 

molluscs. 


Acanthocephala 


Entoprocta 

4. Some to suggest that 

entoprocts are highly 

derived, share a common 

ancestor with these 

groups. 

a. Lack of body cavity 

represents a neotenic 

character.

Rhabditiform larva of a 

hookworm 

Caenorhabditis elegans 

Dracunculus medinensis larvae 

Onchocerca volvulus Loa loa

Anchylostoma (Ancylostoma) sp. 

anterior end 

Necator americanus 

Strongyloides filariform larva Strongyloides filariform larva

Phylum Nematomorpha - Jan.ucc.nau.edu

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