Question

table 11 - 4 internal anatomy of a cephalopod (squid)
structure function
gills paired, feathery organs used for respiration
esophagus thin tube connecting the mouth to the stomach
stomach small sac where food is stored and digested; digestion is entirely extracellular in cephalopods
pancreas small, granular digestive gland that secretes enzymes into the stomach to assist in the breakdown of food
liver large, elongated gland that releases secretions into the stomach to facilitate enzymatic digestion of food
cecum large, thin - walled digestive chamber prominent along the dorsal end of the body
rectum portion of digestive tract leading to anus
ink sac large sac that opens into the rectum and secretes a dark brown or black fluid when the animal is alarmed
anus terminal portion of digestive tract located near siphon
testis (male) produces sperm; located in dorsal end of body tube
vas deferens (male) open - ended chamber that receives and stores sperm
spermatophoric gland (male) coiled, convoluted tubules that package sperm cells into spermatophore packets
penis (male) muscular organ that gathers spermatophores and releases them outside the body where they are transferred by the males hectocotylus to the female during mating
ovary (female) site of egg production
oviduct (female) open - ended chamber that receives eggs from the ovary
nidamental glands (female) produce secretions that form an encasement around the strings of eggs to protect them
retractor muscles long muscles that control the retraction of the siphon and the head
kidneys paired excretory organs located near the systemic heart that filter nitrogenous wastes from the hemolymph and eliminate them from the body
systemic heart large, muscular ventricle that receives oxygenated blood from the gills and pumps it throughout the body
branchial hearts smaller, muscular chambers that receive deoxygenated blood from all parts of the body and pump blood to the gills
check your progress
3.1 is your squid specimen a male or female? explain how you know.
3.2 why are sensory structures more prevalent on cephalopods than on bivalves?
3.3 put the following male reproductive structures in the proper order to represent the correct path of sperm: penis, testis, spermatophoric gland, vas deferens.
3.4 what are the functional differences between the gills of squid and the gills of clams?

Explanation:

3.1

If the squid specimen has testis, vas deferens, spermatophoric gland, and penis, it is male as these are male - specific reproductive structures. If it has ovary, oviduct, and nidamental glands, it is female as these are female - specific reproductive structures.

3.2

Cephalopods are more active and mobile than bivalves. They need to detect prey, predators, and navigate their environment. Sensory structures help them in these activities. Bivalves are mostly sessile or slow - moving and have less need for extensive sensory perception.

3.3

Testis produces sperm. Sperm then moves to vas deferens which stores and transports it. Spermatophoric gland packages sperm into spermatophore packets. Penis releases the spermatophores outside the body. So the order is testis, vas deferens, spermatophoric gland, penis.

3.4

Squid gills are used for respiration and are paired, feathery organs. Clam gills are also for respiration but they also play a role in filter - feeding. Clam gills trap food particles from the water as well as exchange gases, while squid gills are mainly focused on gas exchange.

Answer:

3.1: Determine based on presence of male or female reproductive structures.
3.2: Cephalopods are more active and need better sensory perception.
3.3: Testis, vas deferens, spermatophoric gland, penis.
3.4: Squid gills are mainly for respiration; clam gills are for respiration and filter - feeding.