The document summarizes key characteristics of mollusks. It notes that there are over 50,000 mollusk species that are bilateral and have a mantle that may secrete a shell. They have a muscular foot and a head with sensory organs and a mouth. It discusses their respiratory and digestive systems and life cycles. The document focuses on three mollusk classes: Gastropoda which include snails and slugs, Bivalvia which include clams and mussels, and Cephalopoda which include squid and octopus. It provides examples and characteristics of each class.

2.  50,000 or more species of mollusks.
 Characteristics:
 Bilateral symmetry.
 Body enclosed by the mantle that may secrete a
shell made of minerals.
 A muscular foot that is highly modified among the various
groups of mollusks.
 Head withy sensory organs and a mouth.

3.  Characteristics:
 Aquatic mollusks have gills. Terrestrial mollusks have
lungs.
 Herbivorous or carnivorous. All of them with a complex
digestive system.
 Most of them are hermaphrodites.
 Most of them lay eggs from which a larvae emerges. It
will go under metamorphosis.
 Have a true heart
 Simple to complex nervous system

5.  There are seven mollusc classes. We will
study 3 of them:
 Gastropoda (gastro=body cavity;
poda=foot)
 Ex. Common garden snail, limpets and slugs

6.  There are seven mollusc classes. We will
study 3 of them:
 Gastropoda (gastro=body cavity;
poda=foot)
 Ex. Common garden snail, abalone, turban
snail
 Bivalvia (bi=two; valvia=valves)
 Ex. Clam

7.  There are seven mollusc classes. We will
study 3 of them:
 Gastropoda (gastro=body cavity;
poda=foot)
 Ex. Common garden snail, abalone, turban
snail
 Bivalvia (bi=two; valvia=valves)
 Ex. Clam
 Cephalopoda (cephalo=dealing with
head; poda=foot)
 Ex. Squid, octopus, sepia, nautilus, etc.

8. LIMPET SLUG SNAIL

9.  They have a dorsally located shell
(often coiled).
 They have a well-developed radula.
 Head with mouth and 4 tentacles (2
optic and 2 sensory)
 Muscular foot to crawl.

10. MUSSEL CLAM
COCKLE
SWORD RAZOR

11.  They have no head.
 They have two shells held
together by powerful
muscles.
 They tend to burrow using
the foot.
 Large gills are used for
respiration and filter feeding.
 Water enters and exits
through siphons.

13. OCTOPUS
NAUTILUS SEPIA
SQUID

14.  Internal shell or no shell (like an octopus)
 The foot is highly modified to form a group of
tentacles around the mouth.
 Squids & Nautilus are free-swimming and
move very quickly. Octopuses are found
among rocks or crawling on the bottom of
the ocean.
 Complex brain, two lateral eyes, excellent
eyesight.
 Strong jaw and radula
 Closed circulatory system

16. https://es.educaplay.com/es/recursoseducativos/3732064/