Cephalopods like octopuses, squids, and cuttlefish are one of the most successful groups of mollusks due to several key characteristics. They have advanced nervous systems and eyes. They are highly mobile, using jet propulsion or other methods of locomotion. Their behaviors are also complex, using camouflage and other defenses. With around 800 living species that inhabit oceans worldwide, cephalopods have been able to thrive in various marine environments through their physiological and behavioral adaptations.

1. Presentation on:
“Cephalopod mollusks are one of
the most successful group of
mollusks. Discuss this statement.”
W. GERARD OUEDRAOGO

2. INTODUCTION 2
 Phylum Mollusca
• Is the predominant phylum in marine environments (around 23%
of all known marine species & second largest Phylum with over
100,000 species living in marine, freshwater and terrestrial
environments).
• Mollusks share a few key characteristics, including a muscular
foot, a visceral mass containing internal organs, and a mantle that
may or may not secrete a shell of calcium carbonate

3. 3
INTRODUCTION…

4. CEPHALOPODS…
» One of the seven classes of Mollusca phylum.
» Cephalopods (“head foot” animals), include octopi, squids,
cuttlefishes, and nautiluses.
» About 17,000 named species of fossils (Endoceratoidea,
Bactritoidea…. Squid-like with external shell called orthocones)
» 800 living species - Octopus and common cuttlefish Sepia credited
each with more than 100 species.
4

5. CEPHALOPODS… 5

6. CEPHALOPODS… CHARACTERISTICS
» Exclusively marine and present in all of the world's oceans and
seas.
» Including shallow and deep-water octopuses, open-ocean
middle-water squids, etc.
» They are shell-bearing animals as well as mollusks with a
reduced shell. (Shell when exists is divided by septa).
6

7. CHARACTERISTICS…
» Cephalopods have beak-like jaws at the anterior end and
are carnivorous predators .
» They are characteristically large, active, with complex
behavioral and physiological capabilities
» Present bilateral body symmetry, a prominent head, and a
set of arms (8, 10, 90) or tentacles (muscular hydrostats)
modified from the primitive molluscan foot.
7

8. CEPHALOPODS
CHARACTERISTICS
» All cephalopods show the presence of a very well-developed
nervous system along with eyes, as well as a closed circulatory
system. They are highly advanced and organized.
» The uniting of the major ganglionic centers of the central nervous
system constitutes a brain of considerable complexity
8

9. 9

10. Locomotion, nutrition and defense
Locomotion
 facilitated by ejecting a
stream of water for
propulsion.
 Some swim using all their
arms or web, some wave
small fins along their body,
and others can actually walk
from place to place
Nutrition and defense
 Tentacles and arms are involved.
 Chromatophores (color pigment cells)
and iridocytes (reflecting cells) under
brain control are used for nutrition and
defense through exposition of colors.
 Ink used to disrupt predator’s sense of
visual, smell and taste,…
10

11. Reproduction & life cycle
 The sexes are usually separate in the Cephalopods.
 During courtship the male deposits spermatophores in the female,
either within the mantle cavity or on a pad below the mouth, by means
of a specially modified arm, the hectocotylus.
 All cephalopod eggs have a remarkable amount of yolk, unlike that in
the rest of the Mollusca. Development of the embryo is direct, without
the distinctive larval stages and metamorphoses that occur in other
mollusks.
 Growth is very rapid (exponential and logarithmic phases) and adult
size is reached in about a year (6–24 months)
11

12. 12
1. P. Boyle, (2001) Cephalopods-
Encyclopedia of Ocean Sciences
(Second Edition). Retrieved October 23,
2020 from
https://www.sciencedirect.com/topics/a
gricultural-and-biological-
sciences/cephalopoda.
2. Facts: The Nautilus. Retrieved October
23, 2020 from
https://www.youtube.com/watch?v=nRC
qD5vdUJs.
3. why octopus have three hearts: The
biology behind the octopus anatomy.
Retried October 30, 2020 from
https://www.youtube.com/watch?v=BIQ
FblffD9w