What Is One Problem An Animal Has If It Has An Exoskeleton?

6.2 Skeletons (ESG82)

The skeleton is the supporting structure of an organism. There are three different types of skeletons: hydrostatic skeletons, endoskeletons and exoskeletons.

Hydrostatic skeleton: Water exerts force per unit area on muscular walls, for example, in jellyfish.
Exoskeleton: The stable chitinous or mineralised outer shell of an organism, for example, the vanquish of a grasshopper or prawn.
Endoskeleton: A cartilaginous or mineralized back up structure inside the body, for example, in humans and other vertebrates.

In this chapter we will be looking at support systems in animals and investigating the human skeletal system in some depth.

As you will learn in the chapter History of Life on Earth, many of these structural adaptations allowed animals to motion from water onto land.

The evolutionary evolution of the skeleton (ESG83)

Learners do need to know item from this section on the evolution of skeletons. Rather, it is important that they grasp how course has adapted to office over fourth dimension. This section should be used to reinforce the learner's previous agreement of evolution, covered in before grades, and should lay a foundation for the later chapter on the 'History of Life on Earth'.

Body back up provided by h2o

The primeval forms of life evolved in the oceans. The fact that this is an aquatic environment is key. Water is about \(\text{ane 000}\) times denser than air. The high density of water allows organisms to bladder, due to a physical, upward strength inherent in liquids known every bit buoyancy. Buoyancy allowed organisms to grow and attain big sizes considering the buoyancy force supported the body weight of these animals. However, the density of h2o as well provides resistance to movement, and animals had to adapt to ensure that they were able to movement efficiently through water.

An early accommodation by organisms was the ability to alter the hydrostatic pressure within different chambers of their bodies to enable quick movement. This resulted in the development of hydrostatic skeletons. Animals with this type of skeleton include jellyfish, octopus and sea anemones. The changing shape of the animal reduces both friction and elevate.

Figure half-dozen.ane: The animal above is a jellyfish. It uses its muscles to contract against the hydrostatic skeleton to bring about movement.

Over time, in guild to refine motility and ameliorate protection from predators, some organisms developed a hard chitinous exoskeleton. Exoskeletons first developed in the aquatic environment in aboriginal arthropods. Animals with this type of skeleton include crustaceans like crabs and lobsters.

Effigy 6.2: Crustaceans, such every bit this crab, developed a protective exoskeleton.

Eventually, at that place were some animals that adult a skeletal structure internal to the body, which would become the vertebrate group of animals. These animals take an endoskeleton. Initially, all endoskeletons were made of cartilage, which is a dumbo rubbery type of tissue. Afterwards, endoskeletons of bone evolved.

Effigy 6.3: The beginning vertebrates evolved in the oceans. This fish has an internal endoskeleton that makes it streamlined and allows it to move apace through water.

The adaptation of the skeleton to a terrestrial environment

The ii major requirements for survival on land are the development of a suitable support arrangement and an air breathing machinery. One of the biggest issues encountered by animals moving from water to state was the loss of the effect of buoyancy. In order to counter this, animals needed to develop strong limbs and had to suit the skeleton to support their torso weight on land. Moving effectively on land is essential, particularly if one needs to avert predators, catch prey, or adjust to a item habitat. Unlike skeleton types take solved these problems in different means.

Animals with exoskeletons like arthropods (a form of animals including insects, crustaceans and arachnids) transitioned from sea to state long before the vertebrates (organisms with endoskeletons). A major factor in their success was the exoskeleton which provides attachment for muscles controlling locomotion (motion of appendages). Exoskeletons also provided some protection from dessication (h2o loss).

Figure 6.4: This protrude is an example of a insect. Insects take a protective exoskeleton that made it possible for them to colonise country millions of years ago.

Amphibians with endoskeletons , like frogs and newts, live both on the land and in the water. Their skeletons have adapted to requite advantages in both conditions. They take calcified basic to support their trunk weight under the force of gravity. Their skull is calorie-free and flattened, for both motility on land and a streamlined shape for moving easily in h2o. Their pectoral girdle is adapted to give back up for the forelimbs, which absorb the trunk weight when landing later a jump.

Figure six.5: Amphibians were the get-go vertebrates to colonise land. They brainstorm their life-bike in water, and emerge onto land equally adults.

Depending on their means of locomotion, terrestrial animals needed to adapt their shapes and skeletons to overcome the effects of gravity. Limbless animals, such as snakes, had to overcome drag and friction. Flying animals such equally birds and bats demand calorie-free skeletons and very strong sternums for wing musculus attachment. Animals that support their bodies clear of the basis needed an energy efficient way of maintaining remainder. For this reason, the leg bones of most animals are held straight underneath the body. In this position they act as props or struts and it is the bones rather than the muscles that take nigh of the strain of the body's weight.

Figure 6.6: Land vertebrates oft accept legs placed direct beneath the body. The legs acts as struts, and are the almost energy-efficient way to keep the torso suspended above the basis.

Hydrostatic skeleton (ESG84)

A hydrostatic skeleton is a structure found in many cold-blooded and soft-bodied organisms. It consists of a fluid-filled crenel, which is surrounded by muscles. The cavity is called a coelom and in some animals this cavity is filled with a blood-like substance called haemocoel. The fluid presses confronting the muscles, which in turn contract against the force per unit area of the fluid. The fluid is incompressible and thus maintains a abiding volume against which the muscles can contract. The hydrostatic skeleton prevents the collapse of the body. The muscles in the trunk human activity against the fluid and in doing so bring near movement. If the body is segmented, the pressure of the fluid is localised in a few segments at a time. Hydrostatic skeletons occur in flatworms, round worms, earthworms, starfish and slugs.

Annotation that starfish and other Echinoderms have an outer skeleton of calcareous (chalky) ossicles (little bones) or spicules which are like little spines for protection. This outer skeleton encloses a water vascular organization with tube feet that are moved by fluid force per unit area changes (it serves as a hydrostatic skeleton which controls motion).

Figure 6.7: The animal above is a jellyfish. It uses its muscles to contract confronting the hydrostatic skeleton to bring about motion.

Figure 6.8: The animal depicted higher up is an Echinoderm - a starfish - which uses its tube feet for move.

Advantages of a hydrostatic skeleton

Fluid shape: This allows organisms with hydrostatic skeletons to fit through oddly shaped passages, which is useful for burrowing or swimming.
Strength: Creatures with hydrostatic skeletons tin squeeze between spaces and expand, making a 'prying open' move which allows them to force their way into various regions of stone and soil surfaces.
Healing: Healing takes place faster in organisms with hydrostatic skeletons than in organisms with bone structures. This is because the haemocoel contained within the hydrostatic skeleton is made upwards by and large of water, and thus, can be refilled quickly. This allows many organisms with hydrostatic skeletons such equally earthworms to grow dorsum their torso mass afterward damage.
Lightweight: The hydrostatic skeleton allows the fauna to move in a more than flexible manner every bit it requires very little muscle mass for movement.
Apportionment: The fluid crenel allows apportionment of nutrients and waste material.
Protection: The hydrostatic skeletons cushions the internal organs of the animal from stupor.
Suited to surroundings: Hydrostatic skeletons are suited for life in moist or aquatic environments, depending on the brute's adaptations.

Disadvantages of a hydrostatic skeleton

Structure and surface for attachment: The hydrostatic skeleton lacks a structure and does not have surfaces for the attachment of muscles or limbs.
Lack of protection: There is very little protection for the internal organs.
Dessication: A moist or water habitat is essential for survival of these animals in order to prevent dessication (drying out).
Express strength: Terrestrial animals with hydrostatic skeletons cannot increase their body size as they would plummet under their own trunk weight.

Exoskeleton (ESG85)

An exoskeleton is an external skeleton that supports and protects an animal'south body. The skeleton is not-living and consists of a cuticle strengthened by chitin, a substance secreted past the epidermis (skin). Crustaceans such every bit crabs have their exoskeleton further strengthened past calcium carbonate. There are muscles attached to the inside of the exoskeleton which provides the resistance needed for musculus action.

The exoskeleton is bars to animals such as insects, spiders, scorpions, crabs etc., all of which vest to the Phylum Arthropoda (jointed-legged and jointed-bodied animals). The exoskeleton acts as a hard outer roofing, and is fabricated upwards of a serial of plates or tubes. We often telephone call large exoskeletons `shells'. Exoskeletons starting time appeared in the fossil record during the fourth dimension of the Cambrian explosion and comprises a substantial portion of our fossil record (as you will learn in chapter ten).

Figure six.9: Picture of a spider, a type of arthropod.

Advantages of the exoskeleton

Muscle attachment: The exoskeleton forms the indicate of attachment of internal muscles needed for locomotion thereby providing better leverage for muscle action.
Protection: The exoskeleton protects the soft internal tissues and organs.
Support: The exoskeleton provides structural back up and shape.
Prevents Dessication: The exoskeleton prevents desiccation (drying out) on land.
Light-weight: The exoskeleton of insects has a low density and is therefore lightweight, to allow for flying.
Diverseness: The mouth-parts can be modified for biting, sucking, piercing grasping thus providing for a diversified diet for organisms possessing an exoskeleton compared to those that do not.

Disadvantages of the exoskeleton

Size restriction: The final body size is limited because equally the body size increases, the surface area to volume ratio decreases. The larger the beast, the heavier the exoskeleton, making movement more difficult.
Non-living skeleton does not abound with animal: The overall growth of the animal is restricted due to periodic moulting. Since the exoskeleton restricts growth, moulting is required to accommodate for increases in the size of the fauna.
Vulnerability during moulting: The animate being is vulnerable when it is in the moulting procedure, because the new skeleton is very soft until the new exoskeleton has dried and hardened.
Sites of structural weakness: Exoskeletons are weaker at the joints.

Endoskeleton (ESG86)

Endoskeleton

This skeleton is plant inside the body and can consist of bone (all vertebrates except sharks) or cartilage (sharks) and some endoskeletons consist of both.

Advantages of the endoskeleton

Living: Endoskeletons consist of living tissue, then it is able to grow steadily within the animal enabling some to reach a large size.
Structure and support: The endoskeleton provides shape and structural support.
Structural diversity and adaptation: The bones can vary in size and shape to support the animal's mass.
Flexible: The endoskeleton is jointed which allows for flexible movement and support.
Musculus attachment: The muscles attach directly to the skeletal bones to allow for movement and back up.
Protection: The endoskeleton protects the vital organs such equally the middle and lungs which are protected by the ribcage.
Diversified locomotion: The development of an endoskeleton has allowed for animals to become successfully adapted to locomotion in the surround in which they alive. Vertebrates (organisms with a vertebral column and an endoskeleton) have become adapted to move in a number of different modes of locomotion, east.g. running, jumping, swimming, and flying.

Disadvantages of the endoskeleton

Vulnerable to external environment: The endoskeleton does not offer the beast whatsoever protection from the outside, be it a physical attack or changes in environmental conditions. The animal is therefore very vulnerable.
Susceptible to disease: The skeleton consists of living tissue so is susceptible to infections and disease.

Source: https://www.siyavula.com/read/science/grade-10-lifesciences/support-systems-in-animals/06-support-systems-in-animals-02

Posted by: tiradomanter.blogspot.com