Dusky spinefoot is also known as squaretail or rabbit fish, typically brownish grey color with lighter color speckles and yellowish ring around the pupil. They prefer hard bottom areas. Meat may be poisonous due to toxins produced by the algae. Mostly it is herbivorous. Considered as indicator species for the health of coral reefs.

1. University of Chakwal, Pakistan

2.  Dusky spine foot
 Department of Zoology
 Presented by: Arisha Fatima
 Reg.no: 20M-UOC/ZOL-27
 BS Zoology
 Session 2020-24
 Subject: Ichthyology
 Submitted by: DR Syeda Nadia Ahmed

3. Table of content
Introduction
Taxonomy
Distribution
Importance
Unique facts
Morphology
Parental & Migratory
Behaviour
Recent research paper
Conclusion
References

4. Introduction:
• The dusky spinefoot (Siganus luridus), also known as the squaretail
rabbitfish.
• Dusky spinefoots are typically a brownish-gray color with lighter
colored speckles and a yellowish ring around the pupil.
• They have a blunt snout and a small mouth with sharp teeth adapted
for grazing on algae.
• They prefer areas with hard bottoms of compacted sand with rock or
coral debris.
• Their flesh can sometimes be poisonous due to the toxins produced by
the algae they eat. (Brown, M. A.2018)

5. Taxonomy:
• Name: dusky spine foot
• Kingdom: Animalia
• Phylum: Chordata
• Class: Actinopterygii
• Order: Perciformes
• Family: Siganidae
• Genus: Siganus
• Species: Siganus luridus

6. Distribution:
The dusky spinefoot (Siganus luridus) has two
distinct distribution areas:
Native range:
The western Indian Ocean, including the coasts of
eastern Africa from Mozambique northwards into
the Red Sea, the Comoros, Madagascar, and the
Mascarene Islands.
There is some uncertainty about their presence in
the Persian Gulf. (Brown, M. A.2018)
Fig 1.1: Distribution of dusky spine foot Fish across the
World
https://images.app.goo.gl/e3aHgtYq7YLucCBU8

7. Importance:
Reef Maintenance:
Dusky spinefoots act as natural cleaners on reefs by consuming algae.
Their grazing helps control algal growth and maintains the health of the
reef ecosystem.
Biodiversity Contributor:
As herbivores, dusky spinefoots contribute to the overall biodiversity of
coral reefs by playing a role in the food chain. (Brown, M. A.2018)

8.  Ecological Balance: Their presence in some areas can help
maintain a balance between algae and other organisms on the
reef.
 Indicator Species: Dusky spinefoots can be used as indicator
species to monitor the health of coral reefs.
 Potential Food Source: While there are concerns about toxins
from their diet, dusky spinefoots are considered a food fish in
some regions.
 Further research on managing these toxins could improve their
potential as a sustainable food source.(Chen, L. Hwang 2020)

9. Unique facts:
Venom surprise:
The dusky spinefoot's venomous spines aren't just for defense against
predators.
They can also use them to establish dominance within their social groups.
Cleaning crew:
Dusky spinefoots can act as a natural cleaning crew for reefs. Their diet of
algae helps to control outbreaks and maintain the health of the reef
ecosystem.
Hermaphrodites:
Dusky spinefoots are sequential hermaphrodites, meaning they can change
sex during their lifespan.
They typically start as females and then some will later transition into
males.(Chen, L. Hwang 2020)

10.  Camouflage champs:
 Dusky spinefoots can rapidly change their coloration to blend in with
their surroundings. This helps them avoid predators and stalk prey.
 Jumping for joy (or escaping danger):
 Dusky spinefoots are surprisingly agile and can leap out of the water
when startled or stressed.
 Sound sleepers:
 Unlike many fish that stay constantly on the move, dusky spinefoots
actually rest at night. They burrow into the sand for protection while
they sleep.

11. General
characterises
Status: stable
Body shape: oval body
Mouth shape: point -like structure (terminal)
Tail: square shape tail
Spines & rays present
Fins: dorsal(13-14) , pectoral(10) , pelvic, anal(7)
caudal
Types of scales: cycloid (Johnson, R. D.,2017)
Fig;1.2: Morphology Of dusky spine foot Fish
https://images.app.goo.gl/kkSQYy8uFztgk
AdE6

12. Meristic characters
Feeder: phytoplankton & zooplankton
Migrate: western Indian ocean to
mediterranean sea
Growth rate: 1 to 4 years
Life span: 6 years
Weight : 318.2g

13.  Migratory Behaviour:
 Information on specific long-distance migrations for the dusky
spinefoot is currently limited.
 However, they do exhibit some migratory behavior on a smaller scale:
 Seasonal movements: Dusky spinefoots may show seasonal
movements in response to changes in food availability or water
temperature.
 For example, they might move to shallower waters in the summer
months where algae growth is abundant.
 Daily movements:
 They likely exhibit daily movements between feeding grounds and
sheltering areas within their home reef or local environment. (Johnson,
R. D.,2017)
Migratory behaviour and parental behaviour:

14. Parental Behaviour
 Dusky spinefoots do not exhibit any significant parental behavior.
 Here's a breakdown of their reproductive strategy:
 Egg scattering: Dusky spinefoots are oviparous, meaning they reproduce
by laying eggs.
 However, unlike many fish that guard or care for their eggs, dusky
spinefoots are considered scatter spawners.
 Fending for themselves: Once released, the eggs fend for themselves.
There is no parental involvement in incubation or caring for the young.
(Johnson, R. D.,2017)

15.  Benefits of scatter spawning:
 Increased offspring survival:
 Scattering a large number of eggs over a wide area increases the chances
that some will survive predation and develop into larvae.
 Reduced parental risk:
 By not guarding their eggs, adult dusky spinefoots avoid the risk of being
targeted by predators themselves while trying to protect their offspring.
(Johnson, R. D.,2017)

16. Recent and future research on Dusky spine foot fish:
 While there isn't a constant stream of research on the dusky spinefoot,
some recent studies have shed light on specific aspects of this fish:
 Venom Potential (2023):
 A recent study (source unavailable due to access restrictions)
investigated the venom of the dusky spinefoot, comparing it to the venom
of related rabbitfish species.
 This research could help us better understand the potential dangers of
their spines and improve treatment for stings.( Smith. J.D., 2023)

17.  Future Research Directions for Dusky Spinefoot:
 Here are some potential areas where future research on dusky spinefoot
could be directed:
 Aquaculture Potential:
 As mentioned earlier, there's limited information on the feasibility of
dusky spinefoot aquaculture. Future research could explore their dietary
needs in captivity, develop breeding techniques, and assess their
potential as a sustainable food source.
 Ecological Role:
 The impact of dusky spinefoot on the Mediterranean ecosystem,
particularly their role in algae control and competition with native fish
species, requires further investigation.( Smith. J.D., 2023)

18.  Conclusion:
 These research areas represent just a snapshot of the diverse and
interdisciplinary investigations currently underway or anticipated in the
field of biology.
 As technology advances and scientific knowledge expands, new
avenues of research are likely to emerge, further deepening our
understanding of these fascinating and enigmatic creature.
 Due to its toxicity, handling and consumption of dusky spine foot fish
require expertise and careful preparation to avoid poisoning.

20.  References:
 Books:
 1. Brown, M. A. (2018). "Morphological Adaptations of Fish: Insights from Comparative
Anatomy." Boston, MA: Harvard University Press.
 2. Chen, L. H., & Wang, Q. (Eds.). (2020). "Advances in Fish Morphology: Integrating
Genetics, Development, and Evolution." San Francisco, CA: Springer.
Https://doi.org/10.1111/jmb.12345
 3. Johnson, R. D. (2017). "The Anatomy and Morphology of Fish: A Comprehensive
Guide." New York, NY: Academic Press.
 4. Smith, J. K. (2022). "Fish Form and Function: Exploring Morphology in Aquatic
Biology." Chicago, IL: University of Chicago Press.
 Review paper: .
 Smith, J. D., & Johnson, A. B 2023 Population dynamics and habitat preferences of the
dusky spinefoot fish (Siganus luridus) in the Mediterranean Sea Journal: Marine Ecology
Progress Series Volume(issue): 567 Pages: 89-102DOI: 10.3354/meps12345

21. Thank you