1.
Saba Parvin Haque
M.Sc. Life Sciences
(Specialization in Neurobiology)
from “Sophia College
(Autonomous)”, Mumbai.
selfexplanatory.2022

2.
https://images.app.goo.gl/piS3uYaue1oQrpcG7
https://images.app.goo.gl/sbp3hfRiBxw1BxMv9
Behavior Cases:
1. C. Elegans
2. Cymothoa Exigua
or Tongue-eating
Louse
https://images.app.goo.gl/gjTzXWQmEscAHE4z6
https://images.app.goo.gl/NhwtHy4NB2V2QJ676

3.
Figure: C. elegans Lifecycle
https://www.wormatlas.org/hermaphrodite/introduction/IMAGES/introfig6lr.jpg
Stages: Embryonic Stage, Four Larval Stages
(L1, L2, L3, L4), And Adult Stage (Ad)
Embryo To Adult It Takes 3 Days
Total Lifespan ~20days
https://images.app.goo.gl/x2iNkgGVE5f3WSFT8
Sydney Brenner
Nobel Prize for
physiology or medicine
in 2002 for establishing
C. elegans as a model
system.
https://images.app.goo.gl/x2iNkgGVE5f3WSFT8
Invertebrate Organism
Size: About 1 Mm In Length
Lives: In Temperate Soil Environments
Multicellular Organism
2 Types Of Sexes: Hermaphrodites & Males
Easy To Maintain And Very Fast Life-cycle
Free-living Transparent Nematode
Émile Maupas
first described
Caenorhabditis
elegans.

4.
https://images.app.goo.gl/rHKkXsVynxFSZcCo7
https://images.app.goo.gl/jtYhZSdXEHy2AGCM6
C. Elegans
Behavioral States
Two different behavior patterns
1) It spends 80% of its time "dwelling," feeding on
bacteria Escherichia coli while moving slowly and
staying in a restricted area.
2) At rare intervals, it switches into an alternative
behavioral state called roaming, which involves
rapid locomotion across the lawn.
https://images.app.goo.gl/jtYhZSdXEHy2AGCM6

5.
Olfactory
Imprinting

6.
https://images.app.goo.gl/1PgpPaHHWvfBz8Ld7
This is the only known case of a parasite assumed
to be functionally replacing a host organ

7.
•The tongue-eating louse enters inside the fish through the gills and uses its front claws, to cut the
blood vessels of the fish's tongue, and the tongue falls off.
•So it causes tongue atrophy means a reduction in size due to lack of blood.
•Parasite replaces the fish's tongue by attaching its own body to the muscles of the tongue part and
becomes the fish's new tongue.
• And the parasite does not harm any other part of the host fish but it has been reported by Lanzing and
O'Connor (1975) that infested fish with two or more parasites are usually underweight.
•After replacing the tongue, it feeds on the host's blood and many others feed on fish mucus.
•When a host fish dies, the parasite after some time, detaches itself from the tongue part and leaves the
fish's mouth cavity.
•Then it is seen clinging to its head or body externally. It is not been fully known what happens in the
wild to the parasite.
Gulf of California southward to north of the Gulf of
Guayaquil, Ecuador, as well as in parts of the Atlantic.
Sexual reproduction.
C. exigua are not harmful to humans, except that they will
bite if separated from their host and handled.