Written by Stephan Aarstol
Sharks are the most feared fish that live in water all over the world. Sharks can be seen in every ocean and sometimes even in rivers and lakes. Sharks do not have bones and the structure is completely made of cartilage. The cartilage is a fibrous and tough substance that is not as hard as bones. Sharks can swim only forward and they don't have swim bladder.
Breeds/Types of Sharks
There are about 368 shark species and these are grouped together into 30 families. The sharks are differentiated based on their look and eating habit. Each family has different shapes, fins, color, sizes, personality, teeth, habitat, method of reproduction, diet, and other attributes. Some of the popular species of sharks are angel sharks, hammerhead sharks, reef sharks, blue sharks, great white sharks, and bull sharks.
is a Shark?
: General information of sharks is given
in the form of FAQ.
: Quick facts and information on sharks.
: Simple guide to understand different types of
Kinds of Sharks
: Eight orders of sharks are given with
clear description and examples.
The Anatomy of Sharks
Sharks have only cartilage and unlike bony fish, sharks
are covered with tooth-like, smaller scales called denticles.
The tails of the shark are asymmetrical and an oily liver
helps in buoyancy. Sharks use advanced electroreceptive
system to detect slight electrical fields. A special gill
slit called spiracle is present in front of the first gill
that helps in supplying oxygen directly to the brain and
eyes. Sharks grow throughout their life. The sharks' teeth
are modified placoid scales and they are completely replaceable.
: Complete overview of shark anatomy is given
is explained with a picture.
: Best resource to understand skeleton, muscles,
liver, respiration, and digestive tract of sharks.
Anatomy of Sharks
: General sharks anatomy is explained
in four divisions: head, trunk, precaudal tail, and caudal
: Complete overview of basics of sharks is clearly
explained in the form of FAQ.
: A quick guide on shark teeth.
between Shark and Bony Fish
: Good resource to understand
the difference between a shark and a bony fish.
: Parts of the shark is clearly explained with
a neat picture.
Physiology and Biology
According to their diet, sharks are differentiated into
fast moving hunters, slow moving hunters, and filter feeders.
Sharks never drink water, but they absorb water through
osmosis process. Most of the sharks swallow their food whole
and strong acids in their stomach help to dissolve the foods
completely. The female sharks are normally larger than males
and the eggs are fertilized inside the female's body. The
shark egg development is of many types such as viviparity,
oviparity, and aplacental viviparity.
: External and internal features of a shark
: Digestive system of the dogfish shark is clearly
explained with neat pictures.
Complete overview of the class Chondrichthyes is given with
: Complete overview of viviparous sharks is given
and it includes different forms of uterogestation
Birth in Sharks:
Parthenogenesis in sharks is clearly
explained with case studies.
Sharks have olfactory senses that easily detect even a
drop of blood in the water. Some species have external barbels
that help in detecting prey. Sharks have good vision even
in dim light and they have a layer called tapetum lucidum
at the back of the eye that increases the intensity of the
incoming lights. Sharks detect electricity emitted from
the living animals and even detect magnetic fields that
help them to navigate. The lateral line in the sharks helps
to detect vibrations or motions in water.
: Complete details of sharks sense of smell is
Shark senses are clearly explained with pictures.
: The physiology of the Ampullae of Lorenzini
in sharks is explained.
: A quick guide to understand the lateral line of
Few species of sharks are solitary hunter and few are highly
social. When a shark is approached very closely they perform
a threat display in the form of exaggerated swimming patterns.
Normally, sharks swim at the rate of 8kms per hour, but
when attacking, the shark can reach up to 19kms per hour.
Sharks possess strong social skills, problem solving skills,
and curiosity. Sharks use their spiracles when they rest.
Sharks behavior in different situations is explained.
: Circling behavior of a shark around the victims
: Different behavior of a shark is explained
with clear pictures.
Feeding and Habitat
Sharks are carnivorous and some species eat almost anything.
Sharks rarely vary their diet and few species filter feed.
Each shark uses different strategies to swallow foods. Most
species swallow the whole food or bite food into large pieces.
The social sharks like whitetip reef shark are cooperative
feeders and they hunt in groups to capture the prey. Often,
social sharks are migratory and travel huge distance. Sharks
are normally found in seas and they do not live in freshwater
except few sharks such as river shark and bull shark. Sharks
are found at the depth of 2000 meters and sometimes even
: Complete overview of shark habitat is clearly
: Good resource to understand various shark feeding
: Habitat of different types of shark.
: General eating habits of sharks is given.
Shark Attacks, Predation, and Misconceptions
Only a few sharks are very dangerous to human beings. The
four shark species namely oceanic whitetip, great white,
bull sharks, and tiger sharks are proven to be involved
in unprovoked and fatal attacks on humans. There are many
misconceptions regarding sharks and the popular myth is
that sharks are highly resistant to cancer and disease.
The truth is sharks may get cancer and diseases affect sharks.
Shark attacks and preventive measures are clearly explained.
about Shark Attacks
: Good resource to understand the
truth behind shark attacks. This page clearly explains how
and when shark attacks.
: Informative guide on how to protect themselves
from the attacks of white sharks.
Species in Attacks
: Excellent guide on shark species
that has involved in the attacks on humans.
of Shark Attacks
: This paper analysis the behavior of
sharks and why they attack.
Threat to Sharks
It is found that more than 100 million sharks are killed
every year for recreational and commercial fishing. Sharks
are also killed for shark fin soup. Harvesting sharks before
they attain the sexual maturity largely affects the sharks'
population. Other threats include damage, pollution, habitat
alteration, loss from coastal development, and prey species.
to Whale Sharks
: Complete overview of threats to whale
to Basking Sharks
: Complete overview of threats to basking
: Different types of threats to sharks are
: Complete overview of shark finning and its
effect is explained.
Fishing/Capture and Captivity
Many shark species are kept in captivity in public aquaria
and only few survives in the aquarium condition. Most species
are not suitable for home aquaria. Species suitable for
home aquaria represent financial and spatial investment.
Feeding the sharks with right amount of food is very important
to avoid obesity and fast growth rates.
Sharks at Captivity:
Some quick facts and adverse effects
of sharks at captivity is clearly explained.
: Good information on pet sharks is clearly given
The sharks belong to the class Chondrichthyes, superorder
Selachimorpha, and subclass Elasmobranchii. All the living
sharks are again split into eight orders: Squatiniformes,
Pristiophoriformes, Squaliformes, Carcharhiniformes, Lamniformes,
Orectolobiformes, Heterodontiformes, and Hexanchiformes.
: Complete overview of sharks classification
and characteristics of orders of sharks is clearly given.
of Shark Orders
: Shark orders are compared on the basis
of body shape, dorsal fin, mouth position, reproduction,
habitat, and gill slits.
Sharks - Order Squatiniformes
: Complete information
of angel sharks is given and it includes characteristics
: Complete details of the order Lamniformes
and seven families in the order are explained.
Complete overview of the order Hexanchiformes is clearly
given with examples.
Here are few additional resources on sharks:
: A simple guide to understand hammerhead sharks.
- Physical Characteristics: Best source to understand
whale shark's physical characteristics such as epidermis,
eyes, mouth, and teeth.
: Biology of basking shark such as size, morphology,
and coloration is explained.
Interesting facts about sharks are listed.
: Pictures of male and female urogenital system
with parts marked.
: The habitat and distribution of great
white shark is explained.
: The eating habit and diet of nurse shark is given.
: Size, color, features, life cycle, habitat, and
diet of thresher shark is explained.
: Complete information on migratory patterns and
habitat preferences of the blue shark.
: Quick guide on sharks sleeping pattern
and shark attacks.
all Sharks Dangerous?
: Simple guide that explains different
types of dangerous sharks.
: Complete Overview of bull shark.
: Complete overview of oceanic whitetip
: Complete overview of top ten deadliest sharks.
: Appearance, habitat, diet, and reproduction
of blacktip reef shark are clearly explained.