This document summarizes several types of sea animals. It describes sharks as cartilaginous fish with 5-7 gill slits that are the sister group to rays. Starfish are star-shaped echinoderms with about 1,500 species found in oceans worldwide. Turtles are reptiles characterized by a bony or cartilaginous shell that acts as a shield, and the order Testudines includes both living and extinct species. Porcupinefish are medium to large fish found in shallow tropical and temperate seas that are sometimes called blowfish or balloonfish.

1. Sea animals
By
Apoorva Hemanth

2. Introdution
 Marine biology is the scientific study of organisms in
the ocean or other marine bodies of water. Given that
in biology many phyla, families and genera have some
species that live in thesea and others that live on land,
marine biology classifies species based on
the environmentrather than on taxonomy. Marine biology
differs from marine ecology as marine ecology is focused
on how organisms interact with each other and the
environment, while biology is the study of the organisms
themselves

3. Sea creatures
 Sharks are a group of fish characterized by
a cartilaginous skeleton, five to seven gill slits on the sides
of the head, andpectoral 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 rays. However, the term "shark" has also been
used for extinct members of the
subclassElasmobranchii outside the Selachimorpha, such
as Cladoselache and Xenacanthus, as well as
other Chondrichthyessuch as
the holocephalid eugenedontidans. Under this broader
definition, the earliest known sharks date back to more than
420 million years ago.[1] Acanthodians are often referred to
as "spiny sharks"; though they are not part of
Chondrichthyes proper, they are a paraphyletic assemblage
leading to cartilaginous fish as a whole
.

4. Types of sea animals
Starfish or sea stars are star-
shaped echinoderms belonging to the class Asteroidea.
Common usage frequently finds these names being also
applied to ophiuroids, which are correctly referred to
as brittle stars or "basket stars". About 1,500 species of
starfish occur on the seabed in all the world's oceans, from
the tropics to frigid polar waters. They are found from
the intertidal zone down to abyssal depths, 6,000 m
(20,000 ft) below the surface.

5. Turtle
Turtles are reptiles of
the order Testudines (or Chelonii[3]) characterised by a
special bony or cartilaginous shell developed from
their ribs and acting as a shield.[4] "Turtle" may refer to the
order as a whole (American English) or to fresh-water and
sea-dwelling testudines (British English).[5]
The order Testudines includes both extant (living)
and extinct species

6. Porcupine fish
 Porcupinefish are fish belonging to the family Diodontidae (order Tetraodontiformes),
also commonly called blowfishand, sometimes, balloonfish and globefish. They are
sometimes collectively called pufferfish,[2] not to be confused with the morphologically
similar and closely related Tetraodontidae, which are more commonly given this name.
 Porcupinefish are medium- to large-sized fish, and are found in shallow temperate and
tropical seas worldwide

7. Eel fish
 An eel is any fish belonging to the order Anguilliformes (/æŋˌɡwɪlᵻˈfɔːrmiːz/),
which consists of four suborders, 20families, 111 genera and about
800 species. Most eels are predators. The term "eel" (originally referring to
theEuropean eel) is also used for some other similarly shaped fish, such
as electric eels and spiny eels, but these are not members of the
Anguilliformes order.

8. Climbing perch
The Anabantidae are a family of perciform fish commonly
called the climbing gouramies or climbing perches.
The family includes about 34 species. As labyrinth fishes,
they possess a labyrinth organ, a structure in the fish's
head which allows it to breathe atmospheric oxygen. Fish
of this family are commonly seen gulping at air at the
surface of the water.