Sharks Flashcards
What are the key characteristics of a a Sicklefin lemon shark
- Pale yellow-brown with a white underside
- Open mouth ‘smile’
- Widely spaced dorsal fins of nearly equal height
What are the key characteristics of a coral catshark?
- Nocturnal, hides in the reef in daylight
- Small slender shark
- Numerous black and white spots that often merge to form horizontal bars.
- Dorsal fins angled backwards
What are the key characteristics of a Tawny nurse shark?
- Grey to brownish grey with no markings
- Pair of short nasal barbels
- Wide face and small eyes
- likes to hide during the daytime
- close set dorsal fins of nearly the same height
What are they identifying characteristics of a Blacktip shark?
- Grey with a white underside
- Black tip on 2nd dorsal fin, pectoral fins, ventral fins and lower lobe of caudal fin
- Anal fin pale tip white
- Silver white streak on flank
- Angular snout shape
What are the identifying characteristics of a great hammerhead shark?
- Huge dorsal fin
- Front edge of hammer not scalloped
- Mainly solitary
What are the identifying characteristics of a silvertip shark?
- ## Silver/white margins on ALL fins
What are the identifying characteristics of a grey reef shark?
- black posterior margin of the caudal fin
- Grey with white underside
- Second dorsal, anal and underside of pectoral fins normally black
- Can have a white margin on dorsal posterior edge
What are the identifying characteristics of a Brown-banded bamboo shark?
- Slender body and narrow head
- Brown to greyish brown and my retain hint of juvenile banded pattern.
- Pectoral and ventral fins forward of the dorsal fin
- Rests on the bottom
What are the identifying characteristics of a snaggletooth shark?
- Dent / bump in head between mouth and dorsal fin
- Second dorsal fin far back
- Grey to brown without marking
- Rounded snout
- Gill slits long
- Strongly curved pectoral fins
What are the identifying characteristics of a scalloped hammerhead shark?
- Regular size dorsal fin
- Scalloped hammer shape
- Solitary or in schools
What are the identifying characteristics of an Indonesia Wobbegong shark?
- Small benthic shark
- Alternating brownish bars and saddles on the ventral side
- Nasal Barbels
What are sharks a subgroup of?
sharks are a subgroup of Chondrichtyan fishes and comprise 8 orders, 34 families and around 470 species
What families of shark are we interested in in IOP?
- Carcharinhidae (reuiem sharks)
- Alopidae (thresher sharks)
- Hemigaleidae (weasel sharks)
- Sphyrnidae (hammerhead sharks)
- Rhincodontidae (whale sharks)
- Orectolobidae (wobbegongs)
- Scyliorhinidae (catsharks)
- Ginglymosyomatidae (nurse sharks)
- Hemiscyllidae (bamboo sharks)
What is the importance of sharks to the coral ecosystem?
- Eat = sharks remove weak and sick fish and help ensure that only the healthiest individuals are left to reproduce. Studies have suggested that sharks promote an increase in both biodiversity and biomass in coral reef ecosystems.
- Prey = Larger sharks oftten have very few predators and are at the top of the food web as apex predators (e.g. tiger sharks), however smaller reef sharks are eaten by larger fish including sharks and groupers (e.g. blacktip reef sharks)
- Poop = Rich in nutrients such as nitrogen which fertilises the reef
What are the male sex organs for sharks?
Males have two external sex organs called claspers located on the ventral side of eh body, between the pelvic fins.
How do sharks mate?
during mating, a male inserts one of his claspers into the cloaca of the female to transfer sperm packets (spermatophores).
- The male bites the females in order for this to occur and they often sink whilst mating and the result is pretty clear mating scars present sometimes on both sexes.
What are the three ways, dependent on shark species, that embryos develop?
- Oviparity
- Viviparity
- Ovoviviparity
What is oviparity?
Oviparity = - Egg laying with yolk sac nutrition (mermaid purses). Female sharks lay eggs that attach to rocks or coral.
- The developing embryo relies entirely on the yolk sac for developmental nutrition
What is the gestation period in Oviparity?
8 - 12 months
What shark species are oviparous?
Cat sharks, bamboo sharks
What is viviparity?
Live birth with placental nutrition.
Once the yolk sac is absorbed it elongates and attaches to the uterine wall, forming a yolk sac placenta
What is the gestation period for viviparity?
11-12 months
What species of shark are viviparous?
Hammerheads, grey reef sharks
What is ovoviviparity?
Live birth with “egg eating” nutrition.
Embryos develop initially relying on the yolk sac but after hatching they gain extra nutrition from consuming nearby underdeveloped eggs (oophagy)
What is the gestation period for ovoviviparity?
10 - 15 months
What species of shark are ovoviviparous?
Nurse sharks, tiger sharks
What other reproductive aspects have been seen?
- “Virgin” births have been witnessed in zebra sharks in aquariums
- Embryophagy (embryo eating) has been documented in some ovoviviparous species
What are threats to sharks?
- fished for fins - shark fin soup
- Caught as bycatch in commercial fisheries
- overfishing, habitat destruction, climate change and other anthropogenic pressures.
What is the scientific name for a grey reef shark?
Carcharhinus amblyrhynchos (Bleeker, 1856)
What is the maximum size of a grey reef shark?
up to 2.65 m but commonly around 1.6 m
Where do you find grey reef sharks?
Coastal, lagoon and outer slopes
Are grey reef sharks solitary or form schools?
They can be either solitary or form schools
What is the appearance of a grey reef shark?
- Grey with a white underside
- Usually black on the second dorsal, anal and underside of the pectoral fins
- Can have a white margin on dorsal posterior edge
- Broad black tail margin
What is the distinguishing feature on a grey reef shark?
Black tail margin
What is the occurrence of grey reef sharks in Bira?
Common
what is the position in the water column of grey reef sharks?
Pelagic
Benthopelagic
What is the IUCN status of grey reef sharks?
Endangered
what is the scientific name of the blacktip reef shark?
Caracharhinus melanopterus (Quoy & Gaimard, 1824)
What is the maximum size of the blacktip reef shark?
Up to 2.3 m, commonly around 1.2 m
Where do you find blacktip reef sharks?
Coastal, lagoon and outerslopes
Are blacktip reef sharks solitary or form groups?
Can be solitary or in small groups
What is the appearance of the blacktip reef shark?
- Brownish grey with white underside
- Black tip on 1st and 2nd dorsal, pectoral, anal and lower lobe of the caudal fin
What is the distinguishing feature of a blacktip reef shark?
Black and white stripe dorsal
What is the occurrence of the blacktip reef shark in Bira?
Common
What is the position in the water column of the blacktip reef shark?
Benthopelagic
What is the IUCN status of the blacktip reef shark?
Vulnerable
What is the scientific name of the whitetip reef shark?
Triaenodon obesus (Lesson, 1831)
What is the maximum size of the whitetip reef shark?
up to 2 m but commonly 1.4 m
Where would you find the whitetip reef shark?
Coastal, lagoon and outer slopes
Are whitetip reef sharks solitary or in groups?
They can be solitary or form small groups
What is the appearance of the whitetip reef shark?
- Grey body
- Occasional dark spots on sides
- white tips on 1st dorsal fin and upper tail lobe
- often found resting on reef flats and under ledges in the day
- Blunt nose
What is the distinguishing feature of whitetip reef sharks?
White tips & blunt nose
What is the occurrence of whitetip reef sharks in Bira?
Common
What is the position in the water column of white tip reef sharks?
Benthopelagic
What is the IUCN status of whitetip reef sharks?
Vulnerable
What is the scientific name for the silvertip shark?
Caracharhinus albimarginatus (Ruppell, 1837)
What is the maximum size of the silvertip shark?
up to 3 m
Where do you find silver tip sharks?
Coastal, lagoon and outerslopes
Are silvertip sharks in groups or solitary?
Solitary or small groups
What is the appearance of silvertip sharks
- Grey with pale underside
- White-silvery tips on ALL fins
- Very fast moving shark
What is the distinguishing feature of silvertip sharks?
White-silver tips on ALL fins
What is the occurrence of silvertip sharks in Bira?
Rare
What is the position in the water column of silver tip sharks?
Pelagic
benthopelagic
What is the IUCN status of silvertip sharks?
Near threatened
What is the scientific name for the blacktip shark?
Caracharhinus limbatus (muller & Henle, 1839)
What is the maximum size of the blacktip shark?
up to 2.8 m
where do you find blacktip sharks?
Lagoons, inshore water and reef channel
Are blacktip sharks in groups or solitary?
Can be solitary or in small groups
What is the appearance of the blacktip shark?
- Grey with white underside
- Silver-white streak on flank
- Black tips on 2nd dorsal, pectoral, ventral and lower tail lobe
What is the distinguishing feature of blacktip sharks?
Black tips on pectoral fins
What is the occurrence of blacktip sharks in Bira?
Rare
What position in the water column are blacktip sharks?
Pelagic
Benthopelagic