Butterflies use one-third of their wings for thermoregulation and the other half for flight, camouflage, and mate selection.
Many of the insects we see on a daily basis are examples of Hexapoda.
Adult ants, beetles, flies, and butterflies develop from grub-like or caterpillar-like larvae, whereas adult roaches and crickets develop from wingless immatures.
During the juvenile stages, all growth occurs.
After their final growth spurt, adults do not grow anymore.
The huge variety seen in the insects is due to the variations in wing, leg, and mouthpart.
Their activity as pollinators and their coevolution with flowering plants encouraged insect variability.
Eusocial insects are those that live in large groups with individuals assigned to specific roles or castes.
External chemical signals are used to communicate and maintain a cohesive colony.
The insects have a well-developed digestive system, a respiratory system, a circulatory system, and a nervous system.
There are multiple "hearts" and the segmental ganglia.
You can do the following by the end of this section.
The Greek word meaning "mouth second" means that the mouth develops as a secondary structure opposite the blastopore, which becomes the anus.
The first opening becomes the mouth and the second opening becomes the anus.
The mode of formation of the coelom of the embryo is one of the differences between deuterostomes and Protostomes.
This happens when the archenteron is formed by the separation of the mesodermal pouch from the invaginating layer.
The archenteron develops into the alimentary canal, and a mouth opening is formed by invagination of the ectoderm at the pole opposite the blastopore of the gastrula.
The anus of the alimentary system can be found in the juvenile and adult forms.
Most deuterostomes are indeterminant, meaning that the fate of early embryonic cells is not decided at that point in their development.
The Chordata and Ambulacraria are the major clades of the deuterostomes.
The Chor data includes the vertebrates, the urochordates, and the cephalochordates.
The hemichordates were once considered to be a subphylum and are now included in the Ambulacraria.
The two clades have some interesting features in common.
The vast majority of animals don't have a defined cranium or pedis.
The acorn worms and pterobranchs will not be covered here, but they will share with the echinoderms a three-part (tripartite) coelom, similar larval forms, and a derived metanephridium that rids the animals of nitrogen.
Hemichordates do not have a neural tube, a true notochord or a post-anal tail.
The Greek word for "prickly skin" is "echinos" meaning "prickly" and "dermos" meaning "skin".
There are about 7,000 described living species of exclusively marine, bottom-dwelling organisms.
Sea stars, sea cucumbers, sea urchins, sand dollars, and brittle stars are examples of echinoderms.
Despite the adaptive value of bilaterality, adult echinoderms have arms with multiples of five around a central axis.
The calcareous ossicles are covered by the epidermis.
It is not an appendage like that of arthropods for this reason.
The ossicles can be fused together, embedded in the skin, or reduced to small bones.
Some of the plates are connected to the spine of the echinoderm.
The spine can be locked into place for defense and can be moved by small muscles.
The cells that make up the endoskeleton are produced by dermal cells, which also produce a number of different colors.
In sea stars, fingerlike projections of tissue extend through the body and are used as gills.
Some cells can produce toxins.
There are several different structures in each arm or section of the animal.
Every arm has two rows of tube feet on the oral side, running along an external ambulacral.
The tube feet help in locomotion, feeding, and chemical sensations, as well as serve to attach some species to the substratum.
A diagram of a sea star shows a pattern of pentaradial that is typical of adult echinoderms.
The central ring canal and radial canals extend along each arm.
The animal can move and catch prey with the help of these tube feet.
Water circulating through these structures provides a source of hydration.
In addition to the major organs, the water and hemal systems are involved in the transport of nutrients and gases.
The nervous system in these animals consists of a circumoral nerve ring at the center and five radial nerves.
Different parts of the body have different networks of nerves.
These animals do not have structures similar to a brain or large ganglia.
Depending on the group, echinoderms may have well-developed sensory organs for touch and chemoreception, as well as photoreceptors and statocysts.
A large, baglike stomach can be opened through a short esophagus on the oral side.
If there is a small anus in the arm, the food can be taken to it.
There are cells near the center of the echinoderm disc that are specialized for ultrafiltration of bodily fluids.
The adult echinoderm has a large coelom.
Males and females are not indistinguishable apart from their gametes.
Both males and females release their gametes into the water at the same time.
The bipinnaria of asteroid echinoderms such as sea stars have bilateral symmetry, although each class has its own form.
Asteroidea (sea stars), Ophiuroidea (brittle stars), Echinoidea (sea urchins and sand dollars), Crinoidea (sea lilies or feather stars), and Holothuroidea (sea cucumbers) are the five extant classes.
The sea stars are members of class Asteroidea.
They come in a wide range of shapes, colors, and sizes.
Sea stars have thick arms that extend from a central disk and are different from other echinoderm classes.
At the end of each arm are simple eye spots.
Sea stars use their rows of tube feet to grasp prey.
A sea star can open shells by manipulating its tube feet.
Sea stars have two stomachs, one that protrudes through their mouths and the other that can be found in the center of their body.
A sea star eating a clam can partially open the shell and then eat its stomach into the mollusk.
The process of digestion can begin if the strong adductor muscles of a bivalve are weakened.
You can see the sea star's body plan up close, watch one move across the sea floor, and see it devour a mussel.
The class is called the "snake-tails".
brittle stars have long, thin, flexible arms that are demarcated from the central disk.
The stars move by lashing out their arms or wrapping them around objects.
Their arms are used to grab prey.
The water system in ophiuroids is not used for walking.
Sand dollars and sea urchins are examples of Echinoidea.
These echinoderms are flattened with five rows of tube feet and have a continuous internal shell called a test.
Tubes are used to keep the body clean.
Some echinoids are suspension feeders and others may feed on the remains of plants or animals.
Sea lilies and feather stars are examples.
The feather stars of the sea lilies can move about using leglike appendages that emerge from the aboral surface.
Both types of crinoid are suspension feeders, collecting small food organisms along the ambulacral grooves of their feather-like arms.
The arms were lined with tube feet.
The tube feet are used to move captured food.
In ancient oceans, there were more than 600 species of crinoids.
Many crinoids are deep-water species, but feather stars are found in shallow areas.
The only echinoderms that show "functional" bilateral symmetry as adults are these.
The tube feet are absent on the side where the animal lies.
A bilaterally symmetrical animal has a single gonad and the digestive tract is more typical of that animal.
There are small animals around the mouth.
Some sea cucumbers are suspension feeders and some are feeders.
The brittle star of class Asteroidea, the sea lilies of class Crinoidea, and the sea urchins of class Echinoidea are some of the different members of Echinodermata.
Animals in the Chordata have a notochord, a hollow nerve cord, pharyngeal slit, and a post-anal tail.
Some of the traits are only present in the early stages of development.
There are two clades of "invertebrates" in the Chordata, Urochordata and Cephalochordata.
tunicates live on the ocean floor Lancelets are suspended feeders that feed on organisms.
In the following chapter, the invertebrate chordates will be discussed more.
The worms and tricladid freshwater species do not show the formation of true monogeneans and the trematodes and derived tissues are not included.
The life cycles of trematodes are complex and involve a number of tissues.
Sexual reproduction takes place in the secondary host and primary host of the molluscan.
sponges are very simple in organization, but they perform a lot of the functions of more complex animals.
The ciliated, wheel-like corona is located on their head.
Cnidarians are unique to this group of organisms and represent a more complex level of organization.
They have outer and inner tissue layers.
The nemerteans are simple.
These carry out ribbon-shaped animals have a specialized proboscis digestion in their rhynchocoel and have a well-formed digestive system.
Much of the animal has been closed off.
The mouth is surrounded by a circulatory system that is derived from the coelom and contains large numbers of difference compared to other species.
The nemerteans have more developed excretory and stinging systems than the flatworms.
There are separate sexes and rotifers for cnidarians.
A planuliform or trochophore-like stage is used in the development of nemertean worms.
The asexual Molluscs and Annelids stage are produced by Superphylum Lophotrochozoa.
There are colonies of individual medusa schizocoelous that occupy marine, freshwater, and sea forms.
There are seven Superphylum Lophotrochozoa classes, each of which has variations on the basic Flatworms, Rotifers, and molluscan body plan.
Three classes are described in this section.
Some mollusks have evolved a reduced shell and other have no shell at all.
The body and one eucoelomate are covered by the mantle.
Flatworms are acoelomates, triploblastic forms a mantle cavity which is distinct from the animals.
They have a rudimentary excretory system, but they don't have a circulatory or respiratory system.
In most species of aquatic mollusks, it is incomplete.
The arthropod foot is modified for various purposes.
There are separate sexes for most mollusks.
The number of species and stages precede the number of individuals on Earth.
Vermiform animals are included in Phylum Annelida.
Each segment of a arthropod is partitioned into two parts, with the presence of jointed appendages.
There is a pair of appendages in the basic body plan.
The repeated in each segment.
Traditional classification of these animals is based on their mouth parts.
Modifications of appendages are present in the body subdivisions, number of appendages, and two major groups of annelids.
In aquatic arthropods, there are parapodia with multiple bristles.
Gills and tracheae have no parapodia or bristles.
The clitellum, which arthropods, are found in both aquatic and terrestrial groups of oligochaetes.
The leeches don't have a full internal segment.
Echinoderms are deuterostome marine organisms.
Adults show five-fold symmetry.
The calcareous endoskeleton of animals has trochophores, while the body has ossicles.
Epidermal spines are attached to ossicles and serve in a protective capacity.
Some of the species of the Ecdysozoa have respiratory trees.
The point of entry and exit for sea growth is the chitinous cuticle, which is large enough to cover the body.
The water is pumped into the system.
They have a variety of feeding techniques.
There is a rudimentory excretory system.
Podocytes are cells associated with the free-living Caenorhabditis elegans as well as the hemal system.
A notochord is one of the characteristic features of the Chordata.
Most adults have a fixed number of cells and embryo development proceeds via several larval a hollow nerve cord, pharyngeal slit, post-anal tail and stages.
The tardigrades, sometimes called "water bears," are a group of tiny animals with a small body.
Most tunicates live on the ocean floor, they are pseudocoelomates and have fixed suspension feeders.
Lancelets feed the number of cells as adults.
They are able to feed on a variety of organisms.
The Ambulacraria, which includes the hemichordates and the Echinoderms, can resist a number of adverse environmental conditions.
The radula is used for grinding food.
The stomach is connected to a GI tract.
The parazoan body has a large central opening.
The medusas contract a ring of muscle in their bells as they swim by.
A tube-within-a-tube design is the basis of most sponge body plans.
Sponges don't have the specialized cell types needed.
A design that maximizes the surface area to volume ratio of d. turbellarians is required.
There is a rhynchocoel.
There are cells in _____.
Annelids have a name: Nematoda a pseudocoelom.
There are flies.
The segment allows for different types of protection.
They have _____.
The development of the nematodes can have hexagonal symmetry.
The fluid in the skin is _____.
The cuticle of the nematode is _____.
The human embryo undergoes a cleavage.
There is a human's spine.
They are called crustaceans.
The Chordata's sister taxon is _____.
The tapeworm body plan supports sponges.
How does the circulatory system change?
Caenorhabditis elegans is a valuable model system for biologists because of its Enumerate features.
There should be at least two positive and two negative effects.
Compare and contrast the different types of examples.