Demonstration Sheets for Crustaceans (Lab 6)
(Figures and page numbers are from the 8th edition of Roberts & Janovy)
All exhibits this week are in the phylum Arthropoda, subphylum Crustacea
Subclass Copepoda , Cyclops, Guinea Worm Vector
Cyclops is a freshwater copepod and an intermediate host for Dracunculus
medinensis. Humans acquire the nematode parasite by drinking water containing
infected copepods. Copepods (of another genus) are also intermediate hosts for the fish
tapeworm, Diphyllobothrium latum. 4X
Subclass Copepoda
Parasitic Copepod
The head of the copepod is buried in an artery of a local “spot” or Leiostomus
xanthorus. The body and egg masses of the parasite are outside. The thin, streamlined
shape of the parasite minimizes its impact upon the spot’s ability to swim away from
predators. Specimen
Subclass Copepoda, Family Pennellidae
Salmonicola
This is a common parasite of freshwater fish. See Figs. 34.18-20 (p. 546-47).
Note the following: 1. Swollen bulla which anchors the parasite in the flesh of the host.
2. Two egg masses that trail behind parasite. Specimen, Dissecting scope
Class Branchiura
Argulus Fish Lice
These specimens were collected from fish in the estuary near the Estuarium at
the Dauphin Island Sea Lab. They swarm over the external surface of fish feeding on
mucus covering the fish scales. See Fig. 34.26 (551). Dissecting Scope, Specimen
Class Branchiura
Argulus Fish Lice
Observe the two characteristic saucer-like, circular organs that enable the ectoparasites
to stay on the host as it moves through the water. PS 3000, 4X
Class Cirripedia (= Barnacles), Order Thoracica, Family Cornunulidae
Whale Barnacles
This specimen was removed from the skin of gray whale that had washed ashore
south of Santa Barbara, CA. The barnacles are not parasites, but ectocommensals that
feed on planktonic organisms as the whale swims. The barnacle’s white plates grow
into the whale’s skin. “Whale lice” are found in necrotic tissue around the barnacles
where they probably feed on whale skin. Some have suggested that the breaching
behavior of whales (leaping out of the water) is an attempt by whales to relieve itching
caused by the barnacles. Specimen
Order Amphipoda, Family Cyamidae
Whale Lice
These specimens were collected from the same gray whale as the whale
barnacle on display. Note the sharp tips to the legs which enable the amphipods to
move over the skin of the whale without being washed off. See Fig. 32.32 (p. 555)
Specimen
Class Cirripedia (= Barnacles), Order Thoracica, Family Poecilasmatidae
Gill Barnacles
These small stalked barnacles are true filter-feeders that adhere to the gills of
blue crabs. They are obligate symbionts in that the family is only found in the gill
chambers of crabs. The barnacles do not feed on crab tissue, but rely upon the
respiratory currents of the host to bring food to them. A few small barnacles on a crab
are not a significant burden to the host, who sheds them when it molts. Large crabs,
such as females carrying eggs, do not molt often and the barnacles can cause these
individuals significant harm as they interfere with the ability of the host to respire. This
crab was collected from Bayou La Batre, AL. Specimen
Class Cirripedia (= Barnacles), Order Rhizocephala, Family Sacculinidae
Loxothylacus panopaei
This species infects small stone crabs in the Gulf of Mexico. It appeared along
the Atlantic Coast 1960s after the oyster industry in the Chesapeake Bay began to
culture oysters imported from the Gulf of Mexico. Dissecting
Class Cirripedia (= Barnacles), Order Rhizocephala, Family Sacculinidae
Heterosaccus californicus
This rhizocephalan parasitized kelp crabs along the southern California coast. In
addition, to parasitic castration, the barnacle feminizes male hosts who acquire wider
abdomens than unparasitized males. See the accompanying diagrams. Fig. 34.29 (p.
552) illustrates how the root-system of the barnacles permeates the internal tissues of
the host. Specimens
Order Decapoda
Unparasitized and parasitized kelp crabs. Notice that external stage of the adult
rhizocephalan occupies the same location as eggs on an unparasitized female crab.
Specimens
Order Isopoda, Family Bopyridae, Bopyrid Isopod
These parasitic castrators usually infect shrimp and hermit crabs. Note the
swollen gill chamber containing the parasite. Specimen, Dissecting scope
Order Isopoda, Family Bopyridae
Bopyrid Isopod
This species is commonly found in the gill chambers of local grass shrimp.
Dissecting
Order Isopoda, Family Cymothoidae
Isopod Fish Gill Parasites
These isopods are commonly found on the fins and gills of salt water fish where
they feed upon host blood. They are NOT parasitic castrators. They will abandon hosts
that have been caught and their sharp hooked appendages have startled more than one
inattentive fisherman. Genera in this group bear names such as Cirolena, Rocinela,
Lironeca, Olencira, Nerocila, & Anilocera, They were named by Harriet Richardson at
the beginning of the 20th century. After her death it was noticed that the letters were
anagrams of a woman’s name. Sadly, perhaps, the last genus Ms. Richardson
described was Excirolana.
Order Isopoda, Family Cymothoidae
“Sharksucker”
These ecto-parasites are common on fins of local sharks. Even if they abandon
their hosts following capture, their presence can be noted by surface wounds on the
host where the parasite had been feeding. Specimen
Order Isopoda, Family Cymothoidae
“Surrogate Tongue”
This species of cymothoid occupies space where normally the fish host would
have its tongue. The parasite eats the host’s tongue soon after arrival, attaches itself to
the muscles that move the tongue, and for its efforts takes a portion of its host’s meal
before the host swallows. Other than the absence of the body organ, host fish are
apparently as healthy and vigorous as unparasitized fish. The host is a “ballyhoo” and
was in a commercial bag of bait fish. Specimen
Order Decapoda
Pea Crabs
Members of this family are found in symbiotic relationships with mussels, oysters
and tube worms. Note their narrow bodies which enable them to move into the living
chambers of their hosts and escape detection by predators. Some species feed on their
hosts while others are commensal. See Fig. 34.38 (p. 557). Specimen, Dissection
scope