Grouping Behaviour impacts on the parasitic pressure and squamation of sharks Flashcards
Who wrote this paper?
Humberto G. Ferron and Jose F. Palacios-Abella
When was this paper published?
April 2022
What are possible advantages to grouping behaviour for aquatic vertebrates?
-Dilution Risk
-Co-operative hunting
-Swimming energetics and migration
What disadvantages are there to group living?
-Decreased foraging efficiency
-Increased risk of parasitism
What are monoxenic parasites?
Are parasites with direct life cycles and only need one host to complete their lifecycle
What is squamation?
Is complex anatomical structure that is made up of minute dermal denticles (placoid scales) that are on the skin of sharks
-Arrangement of their scales
What is the purpose of gracile carinated scales?
-Present in active pelagic species
-Involved in reduction of drag
What are rounded and robust scales used for?
-Protection against abrasion and stabilisation of the leading edges of the fins
What is the purpose of star shaped scales?
-Concave and needle like
-Accommodate photophores for bioluminescent species
What is the purpose of hook and thorn like scales?
-Help prevent the settlement of ectoparasites and epibionts
What was the aim of this study?
-To understand the trade-offs and costs associated with social behaviours and the drivers of parasitic interactions with sharks
-To determine if squamation changes with grouping behaviour and increased risk of parasites
How many sharks were studied on parasite richness?
213 shark species
What was found about parasite richness between species?
It varied depending on the species
-Parasite richness increased with frequency of grouping behaviour
What is the squamation like for schooling species of low to moderate speed?
-Have larger crown scale insertion angle than strong-swimming pelagic species, demersal species on rocky substrates, and slow species in open water
What did this study find out about squamation?
That species that show occasional grouping behaviour have greater scale coverage compared to species that show frequent grouping behaviour.
How does grouping behaviour affect parasite richness?
-Grouping behaviour does have an effect on the richness of parasites
-Sharks that show grouping behaviour have greater parasite richness than those that display a solitary lifestyle
What is the squamation like for species that aggregate together?
-They have large crown insertion angles and less scale coverage
-May be a defense against parasite attachment
What helps prove that squamation affects parasite attachment?
-Species that have crowns that point upwards mainly have parasites on mouth cavity and gills, were these scales are not present
How does large crown insertion angles and low scale coverage reduce parasites?
-Reduces the effective surface area for the adhesion and migration of ectoparasites and provide an inadequate microhabitat for the larvae
