Shark introduction Morphology and its behaviour characteristics

Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the Batoidea (rays and kin). Some sources extend the term "shark" as an informal category including extinct members of Chondrichthyes (cartilaginous fish) with a shark-like morphology, such as hybodonts. They generally do not live in freshwater, although there are a few known exceptions, such as the bull shark and the river shark, which can be found in both seawater and freshwater.Sharks have a covering of dermal denticles that protects their skin from damage and parasites in addition to improving their fluid dynamics. They have numerous sets of replaceable teeth.

1. University of Chakwal, Pakistan

2. Topic: Shark Fish
Presented by: Zahra Qayyum
Roll No. 2OM-UOC/ZOL-41
Department of Zoology
Semester: 8
th
Subject: Ichthyology
Session: 2020-2024
Instructor: Dr. Syeda Nadia Ahmad

3. Sharks (Selachimorpha) belong to class chondrichthyes, or
cartilaginous fishes.
There are two main groups of chondrichthyans:
i.The largest is subclass elasmobranchii
ii.The second one is subclass holocephali
Introduction

4. •Four factors spark interest in sharks:
1) Generous funding of research on shark attacks
2) A rise in popularity of recreational shark fishing
3) The opening of china to commerce with the united states
4) The release of the movie “jaws” (castro, 2016).
History

5. General
Characteristics
•Status: endangered
•Body shape: typically fusiform
•Tail: heterocercel
•Fins: dorsal, anal, caudal, pelvic and
pectoral
•Types of scales: scales of shark are called
dermal denticles, the type of placoidscales
•Feeder: bottom feeders
•Life span: 20-30 years. Greenland sharks,
272 years

6. •Kingdom:Animalia
•Phylum:Chordata
•Class:Chondrichthyes
•Subclass:Elasmobranchii
•Superclass:Neoselachii
•Superorder: Selachimorpha
Taxonomy
Fig1.1: Extant shark orders
https://images.app.goo.gl/V4cJPigk3xMcrWqz6

7. •In all oceans of the world
•Certain species survive in cold, deepseaor even in freshwater
•They may be found in stunning tropical reefs, deep water, and even
beneath the sea ice in the arctic.
Distribution

8. •Tiger, bull, blacktip, and nurse sharks were investigated for
morphological variables
•Juvenile tiger and bull sharks -larger caudal fins compared to adults
•This has importance in understanding how body form changes across
ontogeny (irschicket al., 2017).
Morphology

9. •Dorsalfin-1or2
•Pectoralfin-paired-justbehind
thegillslits,
•Pelvicfin-paired-ontheventral
side
•Analfin-betweenthepelvicfins
andthecaudalfin
•Caudalfin-movetheshark
forward.
Fins
Figuer1.2: Shark fins
(https://images.app.goo.gl/xGd3LSswfCy7Hinz6

10. •Comapredtotheirmalecounterparts,
femalesharkshaveskinthatisthicker,
denticledenser,anddenticle
Overlapped(Hagoodetal.,2023).
•Sharkskinismoreliketeeththan
scales
Shark skin
Fig 1.3: Shark Skin
(https://images.app.goo.gl/RKbBebHRQXUdMeJi8)

11. •Males have more distal inclination
in the upper third teeth and wider
upper first teeth than females
(French et al., 2017).
•Up to 30,000 teeth lost in a shark's
lifetime.
•The subterminalmouth found on
the ventral surface of the head
behind the snout, is present.
Shark tooth and mouth
Fig 1.4: Shark teeth and open mouth image
(https://images.app.goo.gl/cxM2pyGbp9gRnrjg9)

12. Shark attacks
•Shark attacks, can lead to human
injury or fatality
•Among the more than 500 known
shark species, only three sharks, are
responsible for most unprovoked
bites and fatalities (hardimanet al.,
2020).
Fig 1.5: Attacking Shark image
(https://images.app.goo.gl/CsKunTgt3VwfC86h6)

13. •Sharks can migrate or not, but when they do there are few reasons,
•Overfeeding in the region
•Changing water temperature or with changing season
•For better breeding chances
•In 2022, researchers used a hidden markovmodel to analyzesatellite tracks from 30
tagged individuals in order to identify unique behavioral stages such as foaragingand
migration (guzmanet al., 2022).
Shark migratory
behavior

14. Maternal investment and
brain evolution
•The research study in 2020 analysed
100 chondrichthyans
•Greater brain size –more maternal
investment (mull et al., 2020).
•Although the mother will not give
the infant any attention, she will
ensure that shark nursery is a safe
environment for the birth.
Fig 1.6: First described nursery in Cuba
(https://www.google.com/url?sa)

15. Public attitude towards
shark
•In 2021, 13,800 questionnaires were
gathered
•Accounting for 92 percent of the
surveys completed
•Researchers discovered positive
view toward shark (giovoset al.,
2021).

16. Interesting facts about shark
No
bones
Excellent
eyesight
Have
electro-
receptor
organsCan go
into
trance
Sharks
age
through
vertebrae
rings
Skin feels
like
sandpaper
Unique
spot
patterns

17. The importance of shark
•Ecological importance
•Sharks are crucial for ocean
ecosystem balance
•Rising significance of
shark tourism
•Shark utilization as meat,
fins, liver, skin, cartilage and
jaws and teeth
Fig 1.7: Shark importance
(https://images.app.goo.gl/upTLZYZE2cwTfiv5A)

18. •Shark conservation
•According to the international union for conservation of nature red
list of threatened species, 397 shark species are endangered (toupinet
al., 2023).
•Local adaption variability in migratory shark
•Using single nucleotide polymorphism, study in 2024 examined
genetic diversity in smooth hammerhead shark.
•Individuals from Pacific coast and the Gulf of California were found
to have adaptive variation (félix-lópezet al., 2024).
Recent researches

19. •Humans influence on shark behavior
•According to a recent study, shark behavior in an isolated marine reserve was greatly
altered by human presence during the COVID-19 lockdown
•Tiger shark detection rates dropped by 67%, while lemon shark detection rates
increased by 43%. (afonso, 2024).
•Initial effects on shark threatened species
•After a no take zone extension, the research conducted in 2024 employed baited
remote underwater stereo-videos to evaluate shark population in the Southwestern
Atlantic region (mottaet al., 2024).

20. •Afonso, A. S. (2024). Humans influence shark behavior: evidence from the COVID-19 lockdown.Ocean & coastal
management,248, 106965.
•Castro, j. I. (2016). The origins and rise of shark biology in the 20th century.Marine fisheries review,78.
•Ebert, d. A., Dando, M., Fowler, S., & Jabado, R. (2021). Sharks of the world: A complete guide (wild nature press)
(illustrated ed.). Princeton university press.
•Félix-lópez, d. G., Rocha-olivares, A., & Saavedra-sotelo, N. C. (2024). Local adaptive variation in a highly migratory
fish: the smooth hammerhead shark sphyrnazygaena.Ecological genetics and genomics,31, 100233.
•Giovos, i., Barash, A., Barone, M., Barría, C., Borme, D., Brigaudeau, C., ... & Mazzoldi, c. (2021). Understanding the
public attitude towards sharks for improving their conservation.Marine policy,134, 104811.
•Guzman, h. M., Collatos, C. M., & Gomez, C. G. (2022). Movement, behavior, and habitat use of whale sharks
(rhincodontypus) in the tropical eastern pacific ocean.Frontiers in marine science,9, 793248.
•Hagood, m. E., Alexander, J. R., & Porter, M. E. (2023). Relationships in shark skin: mechanical and morphological
properties vary between sexes and among species.Integrative and comparative biology,63(6), 1154-1167.
•https://www.Dutchsharksociety.Org/why-do-sharks-migrate
•Https://www.Fisheries.Noaa.Gov/feature-story/12-shark-facts-may-surprise-you
References

21. •Motivarash yagnesh, B., Fofandidurga, C., Dabhiraj, M., Makranirehanavaz, A., & Tanna
poojaben, D. (2020). Importance of sharks in ocean ecosystem.Journal of entomology and
zoology studies,8(1), 611-613.
•Motivarash yagnesh, b., Fofandidurga, C., Dabhiraj, M., Makranirehanavaz, A., & Tanna
poojaben, D. (2020). Importance of sharks in ocean ecosystem.Journal of entomology and
zoology studies,8(1), 611-613.
•Motta, f. S., Rolim, F. A., Athayde, A. C. S., Gragnolati, M., Munhoz, R. R., Chelotti, L. D., ... &
Gadig, o. B. (2024). Initial effects of the expansion and enforcement of a subtropical marine
reserve on threatened shark species.Environmental biology of fishes, 1-12.
•Mull, c. G., Yopak, K. E., & Dulvy, N. K. (2020). Maternal investment, ecological lifestyle, and
brain evolution in sharks and rays.The americannaturalist,195(6), 1056-1069.
•Torres, p., Bolhão, N., Da cunha, R. T., Vieira, J. A. C., & Dos santosrodrigues, A. (2017). Dead
or alive: the growing importance of shark diving in the mid-atlanticregion.Journal for nature
conservation,36, 20-28.
•Toupin, r., Melnick, K., Moharana, T., Curry, B., Gracey, C., Richards, N., ... & Mongeon, p.
(2023). Measuring engagement with shark research in science, news and social media, and
policy: A bibliometric analysis.Marine policy,157, 105829.