● Kingdom - Animalia
● Subkingdom - Eumetazoa
● Phylum. - Acanthocephala
● Class -Eoacanthocephala
● Class -Palaeacanthocephala
● Class- Archiacanthocephala
● The earliest recognisable description n of
Acanthocephala – a worm with a proboscis
armed with hooks – was made by Italian
author “Francesco Redi” (1684). In 1771, “
● koelreuthher” proposed the name
● “Philipp Ludwig Statius Muller” independently
called them Echinorhynchus in 1776. “Karl
Rudolphi” in 1809 formally named them
● Acanthocephala ( Spiny/ thorny-head).
● Name- Greek acantha- prickle and kephala-head.
● Acanthocephala ˈ is a phylum of parasitic worms known as
acanthocephalans, thorny-headed worms, or spiny-headed
worms, characterized by the presence of an eversible
proboscis, armed with spines, which it uses to pierce and
hold the gut wall of its host.
● Acanthocephalans have complex life cycles, involving at
least two hosts, which may include invertebrates, fish,
amphibians, birds, and mammals. About 1420 species have
Acanthocephalans - Adult morphology
● Anterior - presoma( proboscis, neck).
● Main trunk - metasoma.
● Cuticular partition
● Proboscis and sheath
● Longitudinal and circular muscles.
● 2 Hydrastatic system - main Body cavity
and proboscis sheath cavity.
● Eversion proboscis hydrostatic.
● Proboscis movement -lemnisci.
Acanthocephala - Body plan
► Body wall structure
► Absorb nutrients through body
► 5 Major layers-
1. Epicuticle layer
2. Cuticle Layer
3. Striped layer
4. Felt layer
5. Radial layer.
● No respiratory system.
● Absorbs oxygen through tegument.
● No Digestive system in larva and adult.
● Exchange of gases, nutrients and wastes
across body wall by diffusion.
● If present, excretory system consists of 2 protonephridia.
● Nervous system with central ganglion near suclike proboscis receptacle.
● But overall greatly reduced .
● DIoecious, female larger than male .
● Acanthocephala (also known as spiny- or thorny-headed worms) are common parasites
of wildlife and some domestic animal species, but they rarely infect humans.
● Species recovered from humans include Macracanthorynchus hirudinaceus,
Macracanthorynchus ingens, Moniliformis moniliformis, Acanthocephalus rauschi,
Pseudoacanthocephalus bufonis, Corynosoma strumosum, and Bolbosoma sp. M.
hirudinaceus and M. moniliformis are the most common species implicated in human
● Natural definitive hosts include rats (Moniliformis moniliformis), swine
(Macracanthorynchus hirudinaceus), and raccoons (Macracanthorynchus ingens).
● The insect intermediate host varies by species but is usually scarabaeoid or
hydrophilid beetles for M. hirudinaceus and likely M. ingens, and beetles or
cockroaches for M. moniliformis
● Eggs are shed in the feces of the definitive hosts
● The eggs contain a fully developed acanthor
when shed in feces.
● The eggs are ingested by an intermediate host
image , which is always an insect.
● Within the hemocoelom of the insect, the
acanthor image molts into a second larval stage,
called an acanthella image .
● After 6–12 weeks, the worm reaches the infective
stage called a cystacanth image . T
● The definitive host becomes infected upon
ingestion of intermediate hosts containing
● the definitive host,
attach to the wall
of the small
they mature image
and mate in about
● In humans image
the worms seldom
develop to full
● Clinical symptoms of acanthocephaliasis are often
severe, due in part to the mechanical damage
caused by the insertion of the armed proboscis into
the lumen of the host’s intestine.
● No human infections.
● •Major problems fish farms.
● •Difficult to treat.
● Symptoms generally include abdominal pain and
related digestive complaints.
● However, low-intensity or early infections may be
● Seasonal "outbreaks" of disease & mortality. In
ducks n fishes.
1. To control infections in coldwater fish
farms, medicated feed with Bithionol
(2.2-thio bis (4,6-dichlorophenol), is
recommended, at a dose of 0.2 g/kg fish
2. Feeds medicated with Di-N-butyl tin
oxide are also potentially effective