Phylum Mollusca Pak Ismul.pptx

PHYLUM : MOLLUSCA BY YULIA RAHMAWATI (1606103010046) PENDIDIKAN BIOLOGI FKIP UNSYIAH 2016

DEFINITION • The words mollusc derived from the French mollusque, which originated from the Latin molluscus, mean soft, which applied to cuttlefish. The scientific study of molluscs is accordingly called malacology.

CHARACTERISTIC • • • • • •

Have a mantle with cavity Have calcareous shell Unsegmented and have a radula Tripoblastic and Bilaterally symmetrical Have complete disgestive system Ceolomate

MORPHOLOGY OF MOLLUSKS • Usually devide into 2 part : Visceral mass

Head

Head (mouth)

Sensory structure

Foot (large muscle for movement)

heart

Disgestive organs

Excretion organs

Reproduction organs

• The mantle of mollusk covering of visceral mass that secretes the shell. • The shell is comprised of 3 layers, that are perostracum, prismatic, and nacreous layer.

BODY’S SYSTEMS • Nervous tissue made up by ganglia used for feeding, locomotion, and sensory information • Digestive system made up by radula and complete disgestive system

• Circulation of mollusk are open one use hemolymph • Reproduction o sexually only, some reproduce externally or internally. Some mollusk are dioecious or hermaphroditic

radula

gill

Circulation system

radula

CLASSIFICATION • Diverse group, over 100,000 living species (2nd ranking in number among animal phyla) • Of 7 classes, 4 classes covered: • Polyplacophora (chitons) • Gastropoda (gastropods) – snails, slugs, and nudibranchs (sea slugs) • Bivalvia (bivalves) – scallops, oysters, clams, etc. • Cephalopoda (cephalopods) – octopi, squid, cuttlefish, etc.

CLASS POLYPLACOPHORA • Class that cointain chitons. The characteristic are : • • • • • • •

Many-plated mollusk Lives in shallow marine water Feed on algae attached to rock eight overlapping valves muscular foot thick mantle Bipectinate Gills

• Common on the rocky surfaces of the intertidal zone • Head is poorly developed; ventral surface occupied by a broad, flattened foot • Has a dorsal shell composed of 8 overlapping plates, arranged linearly along the anterior-posterior axis

CLASS GASTROPODA • • • • •

Class of Snails and slugs Single external shell Radula for scraping food Moves in wave like contractions through slime Can be hermaphrodites, though commonly not

• Gonochoristic • Veliger larva

• Three evolutionary innovations occurred among the gastropods: changes in the shell, increased development of the head, the embryonic process of torsion

CLASS CEPHALOPODA • Means “head foot” • Includes octopuses, squids, cuttlefishes and chambered nautiluses • Free swimming and predatory • Tentacles with suction cups to grasp prey • Have jaws called beaks to destroy their prey • Has the largest invertebrate brain • muscular foot with tentacles (with suction discs) • thick mantle but no external shell • excurrent siphon (for jet propulsion)

• Can learn to perform tasks • Has complex eyes • Closed circulatory system • Are sexual – internal • Have ink to confuse predators • Closed circulatory system, 2 hearts

BIVALVES • • • • • • • • • • •

Two valves Adductor muscle Gills in mantle cavity Wedgelike foot Sessile Filter-feeders Extend the muscular foot into the sand to anchor it No specific head – but has ganglia The shell is made up from 3 layers Radula absent Reproduction by sexual

EVER YOU SEE THE PEARL? ARE YOU KNOW WHERE IT COMES?