SquidZhong

On Thursday, we dissected squids (phylum Mollusca, class Cephalopoda), creatures stranger than fiction and oddly endearing with their squiggling tentacles and wide eyes. The purpose of the lab was to identify in person the different adaptations and unique body parts of the squid and to observe how a simple funnel, crown of tentacles and fins can operate a weirdly shaped organism which such a big head. Cephalopods are excellent examples of biodiversity, unique organisms that heighten our appreciation when we compare how different they are from humans. We examined the external  and internal parts of the squid carefully because there's a difference between tentacles and arms on the squid and although the innards of the squid may seem just like a mass of goop, there is a  little ink sac like a silvery fish and gills and even a pen, something of an internal shell, similar in touch to plastic--not as simple as a mass of goop. The funnel and the ink sac are very funny but vital parts for escape and movement. When you compare a squid with snails and other slow mollusks, squid seem even more unique. Their 'feet' have evolved into tentacles, of all things--and even two very flexible tentacles, or arms, for additional survivability skills. Squids have some of the largest eyes in the animal kingdom, in fact, the colossal squid is the largest invertebrate alive. In conclusion, squid, like all cephalopods, are very unique from all other animals--certain squid can even fly short distances, their pen is like a glass/plastic pen for their ink, certain squid also have penises 60 cm in length and their feeding system of using jet propulsion, snaring tentacles and a snapping beak is very interesting too, reminiscent of a jungle of living vines and bird all rolled into one organism.
When we dissected the squid, it was very surprising how easy it was to cut through it. There was some confusion between me and my partner about differentiating between the funnel and the ink sac or the pancreas and the digestive glands, or what was the caecum. However, we got our footing eventually. Jaimie correctly identified the squid beak to be constructed of chitin. Throughout the dissection, I thought it was interesting how squid could be "as small as a  thumbnail or as large as a house." Maybe this is because their adaptations are so successful they can survive in any number of sizes. It was a shame throwing the squid into the garbage can; they looked very chewy, destined to be pan-fried.

Here is a picture of a squid,
similar to one we dissected in colour and size. 

Here is a picture of what could've been. 

                                                              EXTERNAL ANATOMY

1.
Our squid, not mutilated even at the tips,
has eight arms and two tentacles,
depending on how you classify
arms and tentacles. The arms are small.
The tentacles are longer and snaring.

2.
Squid have long tentacles with suckers at the tips.
However, arms have suckers that run down the
length of the arms. In this way, tentacles can
grab at prey far away and arms make sure
that the prey stays clung to the squid.
I believe octopi have
8 tentacles,
no arms.

3. The squid will move opposite
to the direction that the jet is propelled
from. The funnel draws water
into the mantle cavity by expanding
its muscles.

4.
a. Tentacles/arms are essential to the squid
as they shoot out to catch prey
and then draw them in and keep a snake-
like grip on them, strangling
before eating.
b. The beak is the kind of like
the second half of the
squid's feeding plan. The beak
allows the squid to eat many large
organisms as it is responsible for chopping
apart the organism
into many digestible pieces.

5.
Mollusks have feet and visceral mass.
The visceral mass in this squid
is contained as shown. While
cephalopods do not have the usual
mollusk feet, they have
tentacles and arms that evolved
from feet.

INTERNAL ANATOMY

1. The squid has two pairs of gills,
one on each side.

2. I think the ink sac empties into the water, surprising
and blinding any predators trying to eat
the squid. I like to think that the squid
does it just to piss off other fish, sometimes.

3. The pen is all that remains of the squid's cell
from its ancestral past. It is located by the mantle,
made up of chitin. Without it, muscles
would not be attached to the squid. 

4. I think the waste exits the
squid through the anus. I remember
that the radula is connected to the
mantle cavity. Maybe the mantle
cavity is connected to the digestive
tract and from the digestive tube,
the waste leaves through the anus.