Lab 4

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Lab 4

• Malacology Mollusks Anatomy and Diversity

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Life Cycle

• Male sheds sperm into water, female receives it
  through its normal course of bringing the water
  into herself for filter feeding.
• Fertilization is internal, some development
  occurs in the ctenidia
• The glochidia larvae are eventually shed and
  attach themselves to a fish where they become a
  parasite. They stay attached until they reach
  maturity.

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Anatomy

• External Anatomy and Orientation

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Clams Are

• Protostomes
• Invertebrates

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Umbo
Periostracum
Prismatic

• The shell of all bivalves is composed of two
  parts, the left and the right valve
• On each side you can distinguish the umbo.
• The shell is composed of three layers (2
  external)
• Periostracum is the dark, outer inorganic
  covering
• Prismatic is the calcareous layer
• Nacreous layer in on the inside of the clam.

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Nacreous Layer
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Internal Anatomy
The mantle lobe is a thin soft tissue sheet
lining the right valve.
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Exhalant siphon
Inhalant siphon
The inhalant siphon are covered with papillae
which have taste buds on them The edges of the
exhalant siphon are smooth. Inside the exhalant
siphon is the epibranchial chamber. The small
hole in the papilla is the anus.
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Posterior Retractor
Anterior Adductor
Posterior Adductor
Anterior Retractor
Anterior Adductor for pulling the shell
together Anterior Retractor for withdrawing the
foot Posterior Adductor pulling the shell
together The protractor muscle is for extending
the foot.
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Used for gas exchange and food capture
Ctenidium
Pericardium
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• Flat and flexible ctenidia means a male or
  non-gravid female.
• Ctenidia are puffy and stiff you have a gravid
• (full of eggs) female

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• Food is sieved out of the water during its
  passage through the lamella.
• The Excretory system consists of a pair of dark
  brown or black kidneys. And a lighter brown
  Kebers organ.
• The kidneys deal with the nitrogenous wastes of
  the clam by producing urine which leaves with
  regular water flow through the animal.

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• The alimentary canal starts at the mouth and
  terminates at the anus.
• The esophagus passes between the protractor
  muscle and the anterior adductor.

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