Zoology Chapter 16
Mollusks
Have a saclike cavity called a coelom that encloses internal organs; most have hard external skeleton (shell); aquatic and terrestrial; includes snails, oysters, clams, octopuses and squids.
Gills
Help extract oxygen from water
Torsion
In gastropods, a developmental process in which the visceral mass rotates up to 180°, causing the animal's anus and mantle cavity to be positioned above its head.
Umbo
Oldest part of the shell
Style Sac
Opens into the stomach and secretes a gelatinous rod.
Mantle
Secretes the shell
Esthetes
So-called "shell eyes" of chitons
Coiling
Special winding of the shell and visceral mass is not the same as torsion
Head Foot
What does cephalopoda mean?
Caudofoveata
Wormlike marine organisms ranging from 2 to 140 mm in length
Crystalline Style
a gelatinous rod which projects into the stomach and is kept whirling by means of cilia in the style sac layers freeing digestive enzymes.
Rhinophores
a pair of tentacles that is modified with platelike folds to increase chemoreception (Opisthobranchs)
Solenogastres
a small group of about 250 species of marine animals similar to caudofoveata however have no radula and no gills and instead have a secondary respiratory system.
Planospiral Shell
all whorls lay in the same plane
Visceral Mass
area beneath the mantle of a mollusk that contains the internal organs
Chromatophores
cells in the skin that contain pigment granules
Suprabranchial Chamber
channels on top of the gills which conducts wastes to the excurrent siphon
Prismatic Layer
composed of densely packed prisms of calcium carbonate laid down in a protein matrix.
Siphuncle
cord of tissue that runs through the chambers of nautilus shell and functions in the removal of seawater from the chambers and in the regulation of the gas content of the chambers
Veliger
free swimming larva of most marine snails, tusk shells, and bivalves; develops from the trochophore and has the beginning of a foot, shell, and mantle
Conglutinate
in females, many glochidia are contained in a packet called?
Glochidium Larva
larva of some freshwater bivalve species which parasitizes fish gills
Nacreous Layer
lies next to the mantle and is secreted continuously by the mantle surface.
Conispiral
more advanced kind of Gastropod shell where the right kidney, auricle and kidney are lost to allow the Gastropod to completely withdraw into the cell.
Periostracum
outer organic layer composed of an organic substance called conchiolin which consists of quinone tanned protein.
Nephrostome
the funnel-shaped opening of the nephridium of some invertebrates such as earthworms; coelomic fluid is drawn into the nephrostome for filtration
Scaphopoda
tusk shells or tooth shells are benthic marine molluscs from the subtidal zone to over 6000 ft in depth.
Hectocotylus
used to pluck a spermatophore from the male mantle cavity and insert it into the female
Gastropoda
A class of the phylum Mollusca that includes snails, slugs, and limpets. These organisms use radula for feeding on algae and protozoa, and have a long foot and cephalized body. They also have simple eyes on eyestalks and a primitive nervous system. They use nephridium to filter and remove waste, and can be monoecious or dioecious.
Sepia
A dark fluid containing the pigment melanin, ink
Open Circulatory System
A pumping heart, blood vessels, and blood sinuses.
Odontophore
A structure at the base of the mouth of most mollusks over which the radula is drawn back and forth in breaking up food.
Opisthobranchs
A subclass of Gastropoda that includes sea slugs and sea hares; mantle cavity lateral/posterior due to detorsion, tend to have a reduction or loss in the shell, operculum (in adulthood), mantle cavity, osphradium, and ctenidia; has structures analogous to ctenidia/osphradium (cerata/rhinophores)
Metanephridia
A type of nephridia in which the inner end opens into the coelom by a nephrostome
Brachial Hearts
Accessory hearts at the base of each gill to increase the pressure of blood going through those cappilaries
Cephalopoda
An active marine predator is found possessing these characteristics: a series of tentacles (modified from the foot), a highly developed nervous system, and elaborate eyes. To which of the following animal classes does this organism most likely belong
Radula
An organ covered with teeth that mollusks use to scrape food into their mouths
Prosobranchs
Anterior gill. Mantle cavity is generally anterior due to torsion.
Bivalvia
Aquatic; clams, oysters, mussels, scallops
Boring
Burrowing into sand
Class Polyplacophora
Chitons , Chitons. Eight valve (shells) imbedded in a thick mantle; large muscular foot.
Capacula
Ciliated adhesive knobs of long tentacles
Monoplacophora
Class of Mollusks that are very primitive. They are abundant as fossils and were thought to be extinct . Characterized by single, cap-like shell resembling that of limpets. They retain some internal segmentation of hear and kidney