VERTEBRATES AND INVERTEBRATES, (PHYLUMS IN BIOLOGY) Summarized Biology Notes

BIOLOGISEDTEAM™

21 Apr, 2022

This should take you about 2 hours to study, we all learn at a different pace so do not worry if it takes you longer than estimated.

To make studying organisms easy, we group them into groups according to their similarities as we discussed earlier, we devide organisms in two groups Vertebrates and Invertebrates, today we'll look closely at them.

INVERTEBRATES

Organisms with no backbone are what we call invertebrates in biology, we have three phylums of invertebrates in biology, Molluscs, Anellids and Arthropods being the largest, down we'll go further and in detail in each of these phylums we mentioned above.

Phylum: Mollusca

Snails, mussels, slugs, oysters and octopuses are all molluscs. They are mostly aquatic and live in seawater or fresh water, but snails Iive on land. Molluscs have unsegmented soft bodies with slimy skin and moist, but not all, have one coiled or two uncoiled hard shells, some molluscs, such as slugs and octopuses, have no external shell or have a much reduced shell. their heads are well developed with tentacles and eyes. Snails are adapted to their environment in such a way that they have coiled hard shells that protect their soft bodies. Furthermore, they have a slimy, flat muscular foot that projects out from the shell, which enables them to move. They have long rough tongues for scraping up food. Mussels are adapted by having two shells hinged together. The shells can be partially open or tightly closed. They attach themselves to rocks with tough, thread-like structures. They feed on tiny organisms in seawater. Octopuses have no external shells, but have shells inside their bodies. They have long projections called tentacles, which they use to move and catch food.

Phylum: Annelida

Annelids are segmented worms. A common example of Annelida is an earthworm most annelids are aquatic, but some live in moist environments on land. They have long cylindrical bodies divided into metameric segments, that is, there is a repetition of structure along the length of their bodies. Since they do not have a hard exoskeleton or endoskeleton, annelids have adapted to their environment by having some fluid inside their bodies to help keep their shape (a hydrostatic skeleton). They also have mucus on their skin to protect them from being damaged. Some annelids have a row of bristles, called chaetae, on the underside of each segment, which help them to grip the surface when they move through burrows.

Phylum: Arthropoda

Arthropods are invertebrates, which means that they do not have a backbone, They include classes such as insects, arachnids, crustaceans and myriapods. Arthropods are the largest phylum because they are the most successful animals. All the arthropods have the following features in common: they have many pairs of jointed legs, segmented bodies and an exoskeleton made of chitin covered With a waterproot cuticle that protects and supports the body. Arthropods are further divided into four subgroups, called classes. These are insects (Insecta) - for example, locusts and butterflies arachnids (Arachnida) - for example, spiders, ticks and scorpions crustaceans (Crustacea) - for example, crabs, lobsters and woodlice myriapods (Myriapoda) - for example, centipedes and millipedes

Class: Insecta

The diagnostic features of insects are:

• one pair of antennae
• compound eyes
• one or two pairs of wings
• three pairs of jointed legs on thorax
• body divided into head, thorax and abdomen
• tracheal system for gaseous exchange

Insects have a hard, rigid exoskeleton that protects them against harsh environmental conditions the exoskeleton is covered with a waterproof cuticle, a waxy tissue that prevents water loss from the insects body by evaporation. Insects have wings that help them to fly away from their predators or fly long distances to seek food. They have different Colours for camouflage to confuse their predators. Insects are small, therefore they do not need much food. Large numbers of insects can live in a small area.

Class: Arachnida

The diagnostic features of arachnids are:

• a body divided into two parts: the cephalothorax (head and thorax) and abdomen
• no antennae but chelicerae to hold the prey
• several pairs of simple eyes
• four pairs of jointed legs on cephalothorax

Class: Crustacea

The diagnostic features of crustaceans are:

• Compound eyes on stilts
• two pairs of antennae
• more than four pairs of jointed legs/five pairs of legs
• body divided into two sections: cephalothorax and abdomen
• very hard exoskeleton helped by calcium salts

Crustaceans have a thick, hard exoskeleton made of calcium that protects their bodies, Crabs and some other crustaceans have strong pincers that they use to catch their prey. Crustaceans have two pairs of antennae as sense organs, which help them to find their way and food. The woodlouse is an example of a terrestrial crustacean.

Class: Myriapoda

The class Myriapoda consists of centipedes and millipedes.

Centipedes

The diagnostic features of centipedes are:

• flattened bodies divided into segments

• one pair of legs per segment

• a head with a single pair of antennae, poison claws and strong mouthparts

Centipedes are carnivores, they paralyse their prey with poison released from their poison claws, strong mouthparts then help them to eat their prey, centipedes have one pair of legs on each segment

Millipedes

New Species Of Millipedes

The diagnostic features of millipede are:

• rounded bodies divided into segments
• two pairs f legs per segment
• a head with a single pair of antennae and strong mouthparts

Milipedes are herbivores, they feed on plant materials, especially leaves. They have strong mouthparts that enable them to eat large quantities of leaves and grind them into fine pieces before swallowing.

VERTEBRATES

In the previous section, we looked at invertebrates. In this section, we are going to look at a group of animals with backbones or vertebral columns. These are called vertebrates, vertebrates belong to a phylum called Chordata. There are five classes of Chordata: fish, amphibians, reptiles, birds and mammals. We are now going to discuss the visible external features used to classify Chordata into the five classes.

Phylum: Chordata

Class: Pisces (fish)

Fish are aquatic and live in seawater and fresh water. Because of its geographic location, Namibia has various fish species. Some of them are Coryphaena hippurus (dolphin fish), Merluccius capensis (Cape hake), Galeorhinus galeus (soupfin shark) and Sardinopus sagax (pilchard). All fish have streamlined bodies, with scales and gills for gaseous exchange. The gills are covered by a bony structure called the operculum, they have fins for swimming and maintaining balance in water. Every fish also has a lateral line, along its length, which is a sense organ that detects vibration in the water. Fish are adapted to an aquatic environment in that they have streamlined bodies that cut the water easily for free movement. Their scales Overlap and face backwards to reduce friction in the water. Fish have tins that help with maintaining balance and steering in water. Most fish are weightless in water because they contain a structure filled with air, like a balloon, called a swim bladder, just below the vertebral column. The swim bladder helps with buoyancy in the water. Fish have a flexible vertebral column, which allows them to manoeuvre from side to side to produce forward motion. The fact that fish have gills for gaseous exchange makes it possible for them to survive in water

The diagnostic features of Osteichthyes (bone fishes) are:

• a wet, scaly skin with thin overlapping scales
• gills with operculum
• two pairs of paired fins and, depending on the species, a varied number of unpaired fins
• a lateral line
• streamlined body shape
• ectothermic.

Class: Amphibia

The class Amphibia includes frogs, toads, salamanders and newts. These animals have smooth, moist skins with no Scales. The adults have four limbs and may live on. land, but they always have to return to the water to breed. Adult frogs lay their eggs in water, where they hatcn into tadpoles. The tadpoles breathe through gills like fish, but undergo a dramatic change, called metamorphosis, to become adult frogs and breathe through lungs and their skin. The only amphibians found in Namibia are frogs. Frogs are adapted for living both on land and in water. Most are adapted to arid conditions. Their bodies are smooth with mucus to prevent them from drying out in dry, hot.conditions. Their nostrils are mounted high on top of the head so that they can expose them easily to the air to get oxygen, while the rest of the body is under water. Their eyes have transparent membranes that are used to cover the eyes when they are under water. This enables them to see clearly even when they are in water. The fact that they can use their skin for gaseous exchange enables them to get dissolved oxygen from water when they are in the water. Amphibians lay soft eggs in water with a jelly-like layer to protect them from being damaged. ladpoles have gills for gaseous exchange, but as they develop into adults they develop lungs to be adapted to breathe on land.

The diagnostic features of Amphibia are:

• moist, thin scale-less skin
• eggs laid in water
• larvae (tadpoles) live in water
• larvae have gills, adults have lungs
• eardrum externally visible
• no teeth present
• ectothermic.

My Favourite Amphibian Is A Salamander

Class: Reptilia

Snakes, lizards, geckoes, crocodiles, tortoises and turtles are all reptiles. Some reptiles, such as lizards and geckoes, live on land; others live in water; or both on land and in water. Reptiles have tough, dry, scaly skins. Most of them have four legs, except snakes that have none. They lay eggs with tough, leathery shells on land and which are resistant to drying. Reptiles breathe with lungs. Reptiles are adapted to their environment by having scales on their skins that protect their bodies against dry conditions. Their eggs have tough shells that prevent them from being damaged because reptiles do not look after their eggs after laying them. Reptiles cannot maintain a constant body temperature, but they can partly regulate their temperature by behaviour. They can bask in the Sun to gain heat or gape to lose heat through evaporation.

The diagnostic features of Reptilia are:

• dry, Scaly waterproof skin
• most have four legs, except snakes which have no functional limbs
• teeth are all the same, except fangs in snakes
• eggs with leathery shells
• ectothermic.

Class: Aves (birds)

Birds include doves, chickens, ostriches, eagles, sparrows, vultures, penguins, flamingoes, pelicans and many others. Birds are closely related to reptiles in that both have scales on their bodies and lay eggs with shells. The theory of evolution says that they evolved from the same ancestors. All birds have feathers on their bodies. Scales can be seen on the lower parts of their legs. They also have beaks to peck and tear food. Birds have wings to fly, but not all of them can fly. Can you think of a certain bird that cannot fly? Furthermore, birds lay eggs with hard shells. Birds are adapted to their environment in that their forelimbs are modified to become wings that enable them to fly. They have streamlined bodies that make it possible for them to cut through the air and minimise air resistance when tlying. Their bodies are covered with feathers that trap air and act as insulation to keep them warm. Birds have light, hollow bones that make them lighter and allow them to fly

The diagnostic features ot Aves are:

• body covered with feathers, lower legs with dry, scaly skin
• mouthparts modified to form beak (no teeth)
• forelimbs modified to form wings
• bones of skeleton are hollow
• eggs with hard, chalky shells
• endothermic.

Birds that Cannot Fly

Common bird that Cannot fly found in Most parts of the world, it's confusing as some think it's not a bird

Class: Mammalia

Mammals include humans, cats, donkeys, cattle, sheep, elephants, whales, bats and rabbits. What do all these organisms have in Common? Mammals have dry skin covered with hair or tur. Female mammals have mammary glands from which they feed their young with milk. They give birth to live young. All mammals have pinnae, or flaps of skin, on their ears. Mammals are adapted to their environment in that their bodies are covered with hair or fur, which traps air and serves as an insulator. Tney have Sweat glands in their skin that produce sweat to lower the body temperature. Mammals have highly developed parental care, meaning that they look after their young. They have mammary glands, which produce milk, to feed their young before they are able to eat an adult die, they generally have few babies.

The diagnostic features of Mammalia are: