Module 5

Created by

Levi Grace

Cards (39)

Phylum Arthropoda 
Segmented body covered by exoskeleton and with jointed appendages
Arthropoda 
insects
arachnids
crustaceans
Arthropoda are of commercial significance as they affect host survival or cause unsightly changes in flesh
Subphylum Crustacea 
Biramous (two parts) limbs
Nauplius larvae
0.1 mm – 3.8 m
Mostly free-living aquatic animals with terrestrial (woodlice), sessile (barnacle), parasitic species
Argulus (Subclass: Branchiura) 
6-6.5 mm (female); 2-3 mm (male)
Dorso-ventrally flat, oval body
Two pairs of antennae and a pre-oral proboscis
With a pair of compound eyes
Body anteriorly covered with dorsal shield
Suckers of first maxillae modified to form main attachment organs
Mobile; can "walk" about the fish surface
Argulosis (Causative agent) 
Freshwater louse
Argulosis (Gross signs) 
Attaches to the skin, fins, buccal or opercular mucosa with 2 conspicuous black spots
Attachment area hemorrhagic or ulcerated
Argulosis (effect on host)
Lesions may become necrotic and ulcerated
Secondary bacterial/fungal infection
Heavy infestation may result in mortalities
Treatment and control (Argulosis)
1. 5 ppm KMnO4, 3-5 min
2. 1 ppm Dipterex, 3-6 h
Copepoda (subclass) 
Wide range of body form
Single median eye usually bright red and in the center of transparent head
Anchored and sessile
Attached firmly or move over host's surface
Mostly ectoparasitic
Parasitic Copepods have a wide range of hosts and microhabitats on hosts
Parasitic Copepods are 1-20 mm long
Most research on fish parasites; less known in marine invertebrates
Parasitic Copepods 
Ergasilus
Caligus
Lernaea
Ergasilidae (Family) 
Resemble free-living copepods in segmentation
0.9-1.5 mm long
Only fertilized females are parasitic
Large, recurved, second antennae (for attachment)
Cephalothorax – first leg-bearing segment
Last segment – associated with swollen genital segment and gives rise to paired egg sacs
Mouthparts on mid-ventral surface of cephalothorax
Ergasilid Infestation 
Attaches on gill filaments, gill arches, on body surface, fins
Extensive gill damage, severe hemorrhage, inflammation associated with feeding and attachment of parasite
Atrophy of gill tips due to blocked blood vessels in gill filaments
Emaciated body; slow, weak swimming, discoloration
Gill damage results in loss of gill surface area for respiration; leads to suffocation
Ergasilid infestation causes mortality, reduced weight, reduced length, reduced fat, increased water content
Treatment and control (Ergasilid)
1. 0.15 ppm Bromex, long bath for 1 week
2. 0.25-0.5 ppm Dipterex (Neguvon, Dylox, Masoten), 24 h
Lernaea (Family: Lernaeidae) 
Anchor worms
1.2-1.4 mm long
Pests in cyprinid and salmonid culture
In commercial aquarium species
Lernaea cyprinacea 
Optimum temperature = 26-28°C
Common in late summer in temperate climates
Prevalent in still or slowly flowing water
Lernaea cyprinacea 
Mainly on Carassius carassius and 45 other cyprinid spp.; on eels, catfish, goby, cichlids, snakehead
Lernaea parts 
Ventral horn
Head lobe
Dorsal horn
First swimming leg
Second swimming leg
Third swimming leg
Fourth swimming leg
Fifth swimming leg
The front part of genital segment is protuberant
Ovulation pore
Caudal furca
Egg sac
Lernaea 
Cephalothorax with 4 conical and soft horns (holdfast); simple anterior ventral pair; bifurcate dorsal pair
Small head projects between the horns
Slim, elongated, cylindrical neck and enlarged trunk carries 4 pairs of legs
Short and rounded end abdomen with 3 segments
Larval stage on gills
Adult females attach on body surface, bases of fins, walls of buccal cavities
Lodge in superficial layers of body musculature
Anchorworm Life Cycle 
1. Eggs hatch (nauplius and metanauplius stages)
2. Molting (5 Copepodid stages - parasites in fish surfae)
3. Cyclopoid adults breed, males die
4. Cyclopoid female penetrates, becomes parasitic adult female and produces eggs
Lernaeid Infestation 
Holdfast and part of the trunk are buried in the host
Most of the trunk and abdomen project in water
Swollen and hemorrhagic skin and muscle
Ulceration leading to muscle necrosis
In infected small fish, parasite can enter the body cavity and damage vital organs
Can hinder feeding and growth
Secondary bacterial and fungal infection
Mortality
Mechanical destruction of epidermis and dermis stimulates inflammation
Respiratory distress when gills are infected
Physical destruction of tissues leading to mortality
Induce pressure necrosis, may secrete histolytic and/or digestive enzymes
Treatment and control (Lernaea)
1. Gross and microscopic examinations
2. Treatment over several weeks to break life cycle at larval stage; embedded females are difficult to eliminate
3. 0.25 ppm trichlorphon (Dipterex, Neguvon, Masoten) can eliminate copepodid but not nauplii or adults
4. 3-5% salt solution for control of larval stage; pond drying and liming
Caligidae (Family) 
Sea lice
Most notorious pests affecting cultured marine fishes
Occur year round
Adults with large, rounded, flat cephalotohorax
Females are larger than male
Caligus – with frontal lunules; 239 sp.
Lepeophtheirus – no lunules; 107. sp.
In tropical and warm temperate waters
Occur year-round
Lepeophtheirus salmonis in cold temperate waters; restricted to salmonids
Caligus elongatus cosmopolitan species; in 80 species of fish
Caligus epidemicus most prevalent in SEA fishes
Caligid Infestation (Gross signs) 
Transparent parasite, non-permanently attached to skin, fins, and gills
3.9-5.1 mm (female)
2.85 mm (male)
5 phases and 8-11 stages
Free-living naupliar stage
Infective copepodid stage
Attached chalimus stage
Free-living, pre-adult stage
Adult stage
Timing of different stages of Caligid development is dependent on water temperature
Caligid Infestation 
Skin lesions leading to ulcerations
Hemorrhagic areas
Secondary bacterial and fungal infections
Mortalities
Osmoregulatory failure due to extensive skin damage
Treatment and Control (Caligid)
1. Freshwater bath, 24 h
2. 0.25 ppm Neguvon, 12-24 h
3. Fallowing, site selection, cleaner fish
Lernaeopodidae 
Highly modified copepods parasitic on marine fishes
Problem in farmed salmonids in USA
Harmful parasite in sparid fish in Japan
On gills, body surface, fins
Adult females are attached permanently by a bulla implanted in the host
Dwarf, short-lived adult male attach to female
Life cycle with 6 stages: copepodid, chalimus, adult
Male dies after copulation
1-6 months – duration of life cycle
Lernaeopodidae Effects 
Poor appetite
Reduced growth rate
Reduced fecundity
Deformed operculum
Mortality
Lernaeopodidae Infestation 
Extensive damage and perforation of body wall into viscera
Pressure on gill filaments reducing length of filaments
Retarded growth of gill filaments
Gill histopathology
Attachment causes greater damage than feeding activity of parasite
Loss of respiratory surface area
Treatment and control (Lenaeopodidae)
1. Gross examination
2. Manual removal
3. On copepodids, 3-4 d interval: 0.85% calcium chloride, 0.2% copper sulphate, 1.7% magnesium sulphate, 0.2% potassium chlorate, 1.2% sodium chloride
4. 0.2mg/kg BW ivermectin, 2-3x/wk
5. 0.2% emamectin benzoate (Slice), 7 d
Lernanthropodae 
On gills of moon fish, sea bass
With more than 100 sp. parasitic on gills
Larger in size than other parasitic copepods; visible with naked eye
Feeds on gill tissues and blood of host fish
In heavy infections, can cause severe damage to gill tissues, respiratory impairment, osmoregulatory failure, secondary bacterial infections, mortality
Isopods 
20-30 mm long
Entire dorsal surface of body divided into several narrow segments
With a pair of eyes
Nerocila, Alitropus
Parasite attaches on skin, mouth, nasal cavity, gills with piercing and tearing mouthparts
Feed on host's blood by a muscular esophagus and grooved paragnath
Isopods signs 
Necrosis of the dermis and gill filaments
Swimming and feeding behavior are affected
Rapid death occurs in 1-2 days
Treatment and control (Isopods) 
1. Mechanical removal
2. 200 ppm formalin until parasite detaches from host
3. Drying and liming of pond