Chapter 10 Part 2: Molluscs Flashcards
What organisms are contained within Class Bivalvia?
Mussels, clams, scallops, oysters, and shipworms
Describe the great variety in size of Bivalves
Tiny seed shells to Giant South Pacific clams
What is the scientific name (genus) of Giant South Pacific clams
Tridacna
True/False: All Bivalves are marine and aquatic
False: all are aquatic but not all are marine
How do Most bivalves feed?
Suspension feeders; depend on ciliary currents produced by gills for food collection
What structures do Bivalves lack?
head, radula, little cephalization
Bivales shells are held together dorsally by what?
Hinge ligament
_____ ____ work in opposition to hold valves together
Adductor muscles
What is an umbo? Where is it located
The oldest part of a bivalve shell; above hinge ligament
What is the main function of the umbo?
Protection
What unique feature do shipworms have on their shell?
Microscopic teeth that allow them to burrow through wood
Describe the circulation process in bivalves
3 chambered heart
Describe the nervous system of bivalves
3 pairs of ganglia; overall poorly developed sense organ
What is the exception to the nervous system being poorly developed? Why?
Scallops; have around 200 ocelli on the shell that contain corneas, retinas, and lenses
What is unique about the digestion of shipworms?
Have a symbiotic relationship with bacteria in a special organ that produces cellulase for wood digestion
What is unique about Tridacna clams in terms of feeding and digestion?
Have a unique relationship with zooxanthellae that produce food for the clam
How do most bivalves move?
By extending the foot out of the shell
Oysters are considered ____. And secrete ____ to attach shells to surface
sessile; cement
Mussels are considered ____. And secrete ____ to surfaces
sessile; byssal threads
How do scallops move around?
Clapping their shells to propel themselves
How many neurons do octopuses have? In what part of their bodies are most of these neurons
found?
500 million; arms
Describe the structure and function of chromatophores.
Speckled across the surfaces like freckles containing pigments for the black, red and yellow colors.
Describe the structure and function of iridophores.
A layer of reflective structures below chromatophores that produce green and blue metallic coloring contain reflectin.
Describe the structure and function of leucophores.
A layer of reflective structures below iridophores produces white colors.
Describe the way(s) an octopus uses papillae. What is the advantage of these structures?
It gives the skin bumps and ridges, allowing it to change its skin’s texture and blend into the environment.
Other than its eyes, what other structure does an octopus use to see?
Skin
How does the “coconut-carrying octopus” demonstrate an octopus’s planning ability?
When traveling far distances with no shelter, they will take coconut halves for protection when they need to stop and rest. Acts as a shell. Has to imagine the future and know that they will need the coconut later on.
Explain the ecological intelligence hypothesis.
Complex behaviors evolved to meet the challenges of predation, foraging, and competition. Especially after the loss of their shell octopuses could have been required to outsmart predators to survive.
Describe cephalopod locomotion.
They move through jet propulsion, where water is expelled through the siphon and pushes them forward
