Lab 4 Study Notes Flashcards
Last phylum in Clade lophotrochozoa?
Mollusca
Second phylum in Clade ecdysozoa?
Arthropoda
What type of development do the invertebrates studied have so far?
Protosome type development
Using the proposed molecular phylogeny, what clade is phylum mollusca in?
Lophotrochozoa
Using traditional morphology based phylogeny, what phyla is mollusca grouped with?
Annelida and Arthropoda
How many classes are in phylum mollusca?
8 classes
What 3 classes of mollusca are studied in lab 4?
Class gastropoda, bivalvia, and cephalopoda
What 4 characteristic features do the animals in mollusca share?
1) a hard external shell 2) a shell-secreting structure called the mantle 3) a visceral mass containing most of the organs 4) a muscular foot used for locomotion
Why is a mussel a bivalve?
Because its shell is made of two parts
Where are mussels found?
Both marine and freshwater habitats but all are aquatic
All bivalves are filter-feeders. What does this mean?
It means they draw in and then expel water, and their morphology reflects specialization for this kind of lifestyle
What are the types of specialization that bivalves do?
1) some are sedentary and anchor themselves in place 2) others can use their muscular foot to slowly locomote
What bivalve was dissected in lab 4?
A mussel
What is the umbo?
It is the bump that is the oldest part of the shell. A mussel’s valves are held together by a hinge near the umbo.
How is a wooden peg used by a mussel?
It is used to keep the shell halves apart but it is necessary to cut through the anterior and posterior adductor muscles before opening it
When the mussel has been opened, what is the flap of tissue first observed?
It is called the mantle and secretes the shell. (If debris gets stuck between the mantle and shell, the mantle will secrete layers around it.)
What are the two mantle flaps observed at one end of the mussel?
These flaps form the excurrent and incurrent siphons
A = excurrent siphon B= incurrent siphon
In a mussel, what has an intricately folded appearence?
The gills and they function in respiration
Tell me about the heart of a mussel. Where is it located? What are it’s characteristics?
It is located in the pericardial cavity which is a greatly reduced true coelom
What does the mussel’s visceral mass contain?
It contains organs like the gonads, digestive gland, intestine and stomach (this all makes up clam chowder! Ewww…)
Which class of mollusca is the largest and most diverse?
Class gastropoda
What kinds of animals does class gastropoda include?
Snails, slugs, whelks, and limpets.
Where can you find the class gastropoda?
In freshwater, marine and terrestrial habitats
What characterizes class gastropoda?
1)Most members have a long flat foot used for locomotion 2) distinct head with eyes and tentacles 3) visceral mass is located dorsally and housed within a spiral shell
The spires of a gastropods shell may show right or left side coiling. What’s this called?
This is called dextral and sinister coiling respectively
How do gastropods eat?
They are herbivores that use their radula to scrape vegetation in their mouth
What gastropods were examined in lab 4?
2 different species of live aquatic pond snails
What sets cephalopods apart from other mollusks?
1) they either have a greatly reduced and internalized shell or no shell at all 2) rather than a large muscular foot, it is differentiated into arms and tentacles that aid in grasping prey 3) they have a closed circulatory system
Nervous system of cephalopods?
Is extremely sophisticated and they are capable of learning complex tasks
Where do cephalopods live?
They are all marine and make for good predators in their habitats
What cephalopod was observed in lab 4?
A squid