Squid Dissection PDF

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Student 20016729 Section 009 Wednesday October 11, 2019 BIOL 212 Squid Dissection Preparing for the Dissection In order to to dissect a squid, I need a scalpel, tweezers, a pair of dissection scissors, pins, a dissection pan, magnifying glass, gloves, and paper towels. If the squid is frozen, it is important to thaw the squid before beginning. Dissection of External Anatomy First we must identify the dorsal (back) side of the squid. The dorsal side usually is a darker colour than the ventral (front) side of the squid. Then we must place the squid in the dissection plate dorsal side facing up. When observing the squid, we first see that there are two fins that are used for steering and staying upright in the water. The main part of the body is the mantle. The mantle is the part of the squid’s body that is just above the head that us used for protection of internal organs and water intake. The skin of the mantle contains tiny dots called chromatophores that can be expanded and contracted by the squid to change the colour of its skin. Just beneath the mantle there is small opening called a siphon which pushes the water out (to propel itself), allows for ink projection, laying eggs, and excreting waste. On the sides of the head—which is ventral to the mantle—there are eyes. Connected to the head, we observed eight short arms and 2 long arms which are called tentacles. Squid have these arms that are equipped

with suckers that are lined with small teeth to grip food and bring it towards the mouth which is called a beak. Around the beak we also noticed a muscular encasing known as the buccal mass. Dissection of Internal Anatomy After observing the external anatomy, we must cut the mantle ventral to dorsal across the mantle. To ensure we do not compromise any internal organs, we held the mantle and squeezed it so that it had a curve at its opening. We made one long incision from the bottom of the mantle, above the siphon, to the tip of the mantle next to the fins. Once we cut the mantle, we pinned it back to expose the internal organs. Following the siphon with a probe, we noticed a couple of skinny silvery structures known as the inks sacs. On the sides of the mantle, there are gills on each side which aid in gas exchange. With the probe, we also identified the branchial hearts at the base of the gills located dorsally to the siphon. These branchial hearts pump blood to each gill. In between the branchial hearts there is a systemic heart which is a 3 chambered heart that pumps blood to the rest of the body. As we continued dorsally, we noticed a clear film of membrane that is protecting the reproductive organs such as the testes in a male or ovaries in a female. Beneath the reproductive organs there is a long pinkish structure called the pen, which is the squids internal shell used for support.

Literature Cited Biologycorner.com. (2019). Virtual Squid Dissection. [online] Available at: https:// www.biologycorner.com/worksheets/squid_virtual.html [Accessed 11 Oct. 2019].

Instructables. (2019). Squid Dissection. [online] Available at: https://www.instructables.com/id/ Squid-Dissection/ [Accessed 11 Oct. 2019]....