More Pseudocoelomates:
The Obscure and the Bizarre
Phylum Loricifera
- Discovered in 1983, off coast of France
- 100 species = initially based on 1
- All species marine, interstitial
! bizarre/specialized creatures,
meiofauna still reveals new animal
species
- “corset bearing”
= loricera, encases most
of the body
- 225-338 µm long
Loriciferan Bauplan
Oral cone
Head
= Introvert
clavoscalids
Neck
Lateral
plate
Intermediate
plate
Ventral
plate
Abdomen
= in cuticular
lorica
Spinoscalids
- mouth on oral cone/complete gut
- no apparent circulatory/gas exchange organs
- protonephridia (1 pair)
Gonochoristic
Slight sexual dimorphism
Male= paired testes,
dorsal
Female= paired ovaries,
seminal receptacle
Fertilization = internal
Higgins larva
=> Robert Higgins
discovered a single
specimen (1974) = termed
it larval priapulid
Phylum Kinorhyncha
= movable snout
Intriguing “animalcules”
Discovered in 1800’s
About 150 species
Nearly all less than 1mm length
Exclusively marine, interstitial
Intertidal to below 1000m
Clearly pseudocoelomate
Metameric condition = taxonomic
controversy
=> Similarities to Arthropods
Kinorhyncha Bauplan
Placids
Tergal
plate
Dorsal
spine
Mouth surrounded
by oral stylets
Body plan similar = main
differences in cuticular
plates
Divided into 13 distinct
zonites
Scalids Head = zonite 1, oral cone &
stylets, 7 spine rings (scalids)
Neck = zonite 2, plates
(placids) => fold over head
when retracted
Trunk = tergal and sternal
plates, dorsal and lateral
spines
Kinorhynch Facts
ecdysis, inelastic cuticle
deposit feeders
Complete gut with digestive
glands
CNS epidermal association
= 10 ganglia around pharynx
Gonochoristic, no sexual
dimorphism
Male = 3 cuticular penial spines
Female = nutritive + germ cells
Internal fertilization, egg laying
Phylum Priapulida
15 extant species, 6 fossil
From Priapus = greek God
of fertility
Have been allied with
several invertebrate groups
Absence of complete
embryological data
= enigmatic taxonomical
status
Cylindrical, vermiform
0.55-20cm length
Priapulid Bauplan
Thin, flexible cuticle
Large hooked spines around
mouth
Introvert (proboscis)
Necklike collar
Trunk/abdomen
Caudal appendages possible
= varies in form/function
Hydrostatic skeleton with
muscles
Priapulid Facts
Predators on i.e. polychaetes
= extending toothed cuticle lined
pharynx
Complete DT some with polythridium
(plates to grind food)
Internal transport = diffusion
Intraepidermal NS
Tactile receptors in caudal appendage
Gonochoristic, paired gonads free
spawners (males first)
Loricate larvae