Lab 2: Life In the Water Part 1 Flashcards
Spiny dogfish scientific name
Squalus acanthias
Size of dogfish shark
Adult males reach one meter, females slightly larger
Aquatic vertebrates are characterized by having what type of body shape that allows them to slide easily through water with reduced resistance
Streamlined or fusiform shape
Main areas of external body of shark
Head with branchial region
Trunk extending to cloacal aperture
Tail (caudal to cloaca)
Main organ of locomotion in sharks that provide the propulsive thrust for swimming
Caudal fin
Asymmetrical-most of the fin lies below the vertebral column. Making the lower lobe larger than the upper lobe.
Shark caudal fins types are known as ……
Heterocercal - lower larger lobe
Placoid scales
What are they homologous to
Each scale consists of a basal plate embedded into the dermis of the skin and a sharp point protruding from the skin and pointing caudally, hence the skin feels roughy when you move your hand over it from tail to head.
Homologous to teeth
Sharks colouring
Grey colour dorsally and lighter centrally. This is known as countershading.
Helps organism be less visible when viewed from below or above
Other fins on shark
Anterior dorsal fin
Posterior dorsal fin
Why are they called spiny dogfish sharks?
Each of the dorsal fins bears a spine on the anterior margin
Life span of dogfish and how can you tell
25-30 years
Concentric rings laid down during growth of hard parts of scales
Pectoral fin function
Pelvic fin functions
Steering
Males-stuff, spined copulateit steuxures called claspers. These fins are supported by cartilaginous fin rays called ceratotrichia
Sharks have what type of eye
Unique eyelids of sharks
Well developed lateral eyes
Immovable eyelids
Lateral at each corner of the mouth of sharks is a ________ which contains a _______ supported internally by a thin rod of ______
Labial pouch
Labial fold
Cartilage
Teeth of dogfish sharks are modified…..
Teeth arrangement and function
Placoid scales, arranged in rows
First two are ones in use at any one time. The teeth are extremely sharp and replaced when worn by teeth from the back rows. Teeth are used for grasping and tearing prey, not chewing.
External nostrils of dogfish sharks are called ______. They are open on the ______ surface of the snout.
Nares
Ventral
How does water enter and exit the nares of dogfish sharks
A flap of skin separates the opening into a medial excurrent and a lateral incurrent aperatue. Water flows into the incurrent aperature to the olfactory organ within, then out the excurrent aperture.
The five external openings anterior to the pectoral fin are the ______
How are they separated
External hill slots
Strips of tissue unlike bony fish that have a common opening of the gills by an operculum
Spiracle
Caudal to the eye is a reduced gill slit
Spiracle valve is a flap of tissue that can cover this opening.
Water can enter the spiralled when the mouth is occupied with prey
A reduced gill called the ______is present on the wall of the spiracular valve
Pseudobranch
Patches of different pores on the dorsal and ventral head region belong to the _______ or ______
If you press on the skin of the head, what happens?
Ampullae
Lorenzini
Jelly-like fluid will exude from the press
The ampullae are ________ that can detect the small electric field around living organism and can sense the presence of prey even when it is not visible.
Sensory structures
The ampullae are derived from what sensory system and what does it do
Lateral line
Detects low frequency vibrations and imparts a sense of “distant touch” to fishes
The main canal of the lateral line system is located where?
On the lateral body surface and it’s position is indicated by a thin horizontal stripe along the side of the body