Overarching Theme Adaptation ANIMALS What characteristics do all animals share?What are the important trends in animal evolution? Big Idea Echinoderms, Invertebrate Chordates and Chordates show similar adaptations such as an endoskeleton and deuterostome embryo development. The adaptation of a notochord is first seen in Invertebrate Chordates.PHYLUM ECHINODERMATA Echinos=spiny, Derm=skin-examples include sea stars (starfish), sea urchins, sand dollars, sea cucumbersGeneral Characteristics-difficult to place in sequence of animals because have some complex adaptations and others that are simple-pentaradial symmetry = as adults have five similar parts arranged in circle around a central point, unique to this phylum-larvae are bilaterally symmetrical, showing their evolutionary link to more complex animals

-exclusively marine, adapted to a bottom-dwelling existence-name echinoderm derived from their characteristic spines (= ossicles), made of hard calcareous bits embedded in their skin-have an internal skeleton (endoskeleton), composed of interlocking calcite plates-have tube feet, which are versatile structures with tiny valves, muscles and suction cups used for locomotion, gas exchange, feeding, attachment, and sensory reception!-on the skin are pedicellaria = grasping appendages that function in food gathering, cleaning, and defense against predatorsi) Feeding and Digestion-depends on lifestyle, some echinoderms are hunters while others are scavengers-most use tube feet to capture and pry apart shells of preyii) Reproduction-Echinoderm sexes are generally separate -Fertilization and development of young are external, larval stage in life cycleiii) Respiration-gas exchange occurs in water, O2 diffuses into coelom and CO2 diffuses out-exchange surface is a skin gill, a membranous surface-gas exchange also occurs in soft tissues of tube feetiv) Circulation-lack a heart and blood-functions of circulatory system replaced by water vascular system and digestive glands that extend throughout body delivering nutrients to cellsv) Excretion-no specialized system, done by diffusionvi) Nervous System-ring of nervous tissue in central area with branch nerves that extend throughout bodyvii) Movement-Contains a water vascular system, a sophisticated hydraulic system used for movement and feeding-water enters body through a sieve plate (=madreporite) at the base of each arm or in centre of body-water then moves through stone canal to ring canal and out to tube feet-like a partially filled water balloon, at outer end is tube foot with suction-cup structure, at interior end in ampulla, a muscular sac that can contract, forcing water into tube foot so it extends and movesviii) Ecological Role-significant role in marine food chainsix) Taxonomy A) Class Asteroida (Sea Stars)-5-20+ arms-eyespots located on tip of each arm-predators-push stomach out of body through mouth to devour prey-can regenerate lost or damaged arm if enough of central section still remains, but is very slow-gills protrude through skinB) Class Echinoidea (Sea Urchins and Sand Dollars)-look like bristling balls of spines-skeletal system fused into a solid spheroidal casing-herbivores-possess a chewing apparatus (=Aristotles lantern) that is a ring of five teeth within their mouth that clip off bits of algae-sand dollars are essentially flattened sea urchins-living ones have a velvety dark purple or black coat of short spines-ingest heavy bits of sand to serve as ballast, so they dont get swept away by wavesC) Class Holothuroidea (Sea Cucumbers)-look like jelly-filled cucumber!-have soft spines and tube feet-endoskeleton plates not connected together-move by tube feet assisted by expanding and contracting their body in wavelike movements-some tube feet modified into ring of sticky tentacles around mouth for trapping food particles-use branched respiratory trees to breath and for excretion, located in anus!

Confirm Your Learning Seastar Anatomy SheetLearning Activity Seastar Dissection

PHYLUM CHORDATA - INVERTEBRATE CHORDATES- Important evolutionary link between invertebrates and vertebrates- Have additional chordate features that echinoderms lack- Genetic studies show that tunicates (type of invertebrate chordate) are closest invertebrate relative to vertebrates.General Characteristics Have 4 distinctive features linking them to vertebrate chordates dorsal tubular nerve cord notochord flexible, rod-like structure that extends length of body, precursor to spinal column, in chordates disappears after early embryonic stage and develops into bone/cartilage and provides place for muscles to attach pharyngeal pouches at one time used for filter feeding, later as gill-like structures, thought to be evidence of the aquatic ancestry of all vertebrates postnatal tail primarily for locomotionTaxonomyA) Subphylum Cephalocodata - Lancelets-small, fish-like animals without scales that burrow their bodies into shallow seas-clear skin, so organs can be seen-arrangement of segmented muscle blocks similar to that in vertebrates B) Subphylum Urochordata - Tunicates -often called 'sea squirts' because, if threatened, they eject a stream of water through a siphon to distract predators-adults have a sessile, saclike body-only larval stages show typical chordate features

PHYLUM CHORDATA - VERTEBRATE CHORDATESGeneral Characteristics-more than 99% of all chordates are in subphylum Vertebrata-vertebral column (backbone) made of individual segments called vertebrae-dorsal, hollow nerve cord (spinal cord)-endoskeleton that supports and protects animals body, grows as animal grows-ventral muscular heart with two, three or four chambers, closed circulatory system-kidneys for excretion and osmoregulation -paired appendages which may be fins or limbs.TaxonomyClass Agnatha = no jaws

-Agnathans are marine animals but migrate to freshwater to spawn-are ectoparasites on some fishes-similar to fish, but with two very noticeable differences 1. no jaws, have circular mouth2. body devoid of scales or paired fins-Examples of Agnathans; lamprey, hagfish Class Chondrichthyes Chondros=cartilage

-These are cartilaginous fish. Their skeleton is not made with bone, but cartilage. Only their teeth are bony; therefore, only their teeth can be fossilized.-Chondrichthyes are expert hunters, and feed on everything from mollusks to mammals-Due to the absence of air bladder, they have to swim constantly to avoid sinking-Heart is two-chambered (one auricle and one ventricle).-sexes are separate, fertilization internal-Many chondrichthyes have an excellent sense of smell, which is used to detect prey from far distances-have special sensory organs called lateral lines that detect vibrations in water-as they near prey, use sight and receptors that detect bioelectrical fields given off by animals -examples of Chondrichthyes: sharks, skates, raysClass Osteichthyes Osteo=bones

-These are the bony fish. Their skeletons are reinforced with calcium, making them stronger and stiffer than the Chondrichthyes -Heart is two-chambered (one auricle and one ventricle)-They are ectotherms, thus rely on external heat sources to maintain working body temperature-Sexes are separate, fertilization is usually external-There are two types of Osteichthyes: the lobe-finned fish and ray-finned fish. -The Coelacanth, a lobe-finned fish gave rise to amphibians. Uses lungs to breath and has 4 fins with muscular lobes and joints similar to those found in terrestrial vertebrates

-the ray-finned fish have thin, flexible skeletal rays-their gills differ from Chondrichthyes gills in that they are covered by an operculum=bony protective flap - -- - -remain buoyant using swim bladder-examples are: tuna, salmon, seahorsesClass Amphibia Amphi=both, Bios=life

-first animals to move onto land, but only partially adapted to life on land (similar to the evolution of mosses from aquatic plants)-animals faced several challenges to live successfully on land; had to overcome differences in buoyancy, O2 concentration, water loss and temperature-amphibians are tetrapods (4 legged animals) -lay eggs in water-as their name suggests their lifecycle depends on land or water, and they usually live in both, although a few species are entirely terrestrial or entirely aquatic.-the typical amphibian lifecycle -how amphibians breathe depends on stage in lifecycle; use gills as larvae, use skin and lungs as adults-three chambered heart (two atria, one ventricle)-ectotherms-Sexes are separate. Fertilization is external. -examples of amphibians are; salamanders, newts, frogs, toads, Ichthyophis (Limbless amphibia)Class Reptilia - Repere or Reptum=to creep or crawl

-Reptiles are the first tetrapods to produce amniotic eggs; this is important adaptation for terrestrial lifestyle as not reliant on water for reproduction-amniotic eggs =egg that provides complete environment needed for embryo to develop including yolk sac for nutrition, internal membranes and external outer shell-They have very tough skin that contains keratin. As a result, they are not tied to water the way the amphibians are, fully adapted to life on land -Most reptiles swallow their prey whole, and have teeth designed for gipping and ripping, not chewing food.-reptiles have adapted unique sense organs; good vision but sense of smell often more important e.g. a snake smells its surroundings by sticking out its forked tongue, some snakes haveinfrared-sensitive receptorsin deep grooves on the snout, which allow them to "see" the radiated heat of warm-blooded prey mammals.-ectotherms-three-chambered heart, similar to amphibians, except crocodiles who have four chambers and thus can move more quickly-respire using lungs-Sexes are separate. Fertilization is internal-examples are; chameleon, gecko, alligator, turtle, pythonClass Aves Avis=bird

-characterized by wings, feathers, and lack of teeth (have gizzard like annelids)-most diverse of all terrestrial vertebrates-collection of adaptations has enabled ability to fly such as; forelimbs modified into wings, endoskeleton is fully ossified (bony), long bones are hollow with air cavities (allows strength without mass), large sternum for attachment of breast muscles used to flap wings, air sacs extend from lungs into internal body systems to supplement respiration-evolved from reptile ancestor, can see in scaly skin on legs and amniotic eggs, also similar nesting behaviours-How are bird eggs different from reptile eggs? Bird eggs have hard calcite shell; reptilian eggs are soft and leathery-Heart is completely four- chambered. -They are endotherms so are able to maintain a constant body temperature and generate body heat internally-Sexes are separate. Fertilization is internal.-Some examples are; ravens, hummingbirds, wrens, parrots, chickadees...Class Mammalia - Mammalis=of the breast

-unique characteristics of the mammals include; females have milk producing mammary glands to feed young, hair or fur, diaphragm, four types of teeth, sweat glands, large cerebrum (lobe of brain where sensory input is interpreted and conscious thought occurs), external ears-large brain requires extended period of maternal care, longer than in any other animal group-endotherms-heart is four- chambered-respiration is by lungs-are three major groups of mammals, taxonomy based on reproductive methods

-Monotremes -lay eggs, once egg hatches offspring receive nourishment from mothers mammary glands-examples; only the duck-billed platypus and echidna-Marsupials-offspring born very underdeveloped, following birth they crawl into pouch where they continue to develop and are nourished by milk-only North American marsupial is the opossum, all others live in Australia-examples; kangaroo, cuscus, wallaby-Placentals-internal placenta and umbilical cord in female provides food and O2 to developing embryo and removes waste-examples; whales, giraffes, badgers, gorillas, wolves, mice, humans Learning Activity Frog Dissection

Connections to Biological Theme Describe the evolutionary advantage of the notochord, first seen in invertebrate chordates.Advantageous because provides a rigid structure for muscle attachment, yet flexible enough to allow more movement than, for example, the exoskeleton of the Arthropods.The flexibility of the notochord enables the body to bend, rather than shorten, during contractions of muscle segments, allowing side-to-side motion of the body and tail. Embryos of vertebrates have notochords today, as it retained a key role in signaling and coordinating development even as it was lost in most adults (replaced by bone or cartilage).____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Compare the adaptation of metamorphosis in amphibians versus insects.Amphibiansmetamorphoseby changing selected parts of their body. In frogs, for example, the tail is lost, and the legs are added. The mouth changes from a narrow one to a wide one. The eyes bulge out in the adults, and the gills disappear. The intestine shortens a great deal, and teeth appear within the mouth. The lungs appear. In salamanders, less drastic changes occur, but they do occur the same way.

In some insects, the entire body is torn down and completely rebuilt while the animal is inside the cocoon. It was thought that even the brain is included in this process, but experiments show that the adult butterfly retains some of the memories and experiences it had when it was a caterpillar. Therefore, amphibians can continue to function (move, escape enemies, if not feed) while changing from an aquatic animal to a land animal. Insects, however, cannot do the same. They must remain immobile, inside a protective cocoon, while they metamorphose.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Why is the amniotic egg considered to be one of the most important adaptations to life on land?The transition from the ocean habitats to the aridity (lack of water) of dwelling on land required several adaptations from the aquatic life style. The most striking is the severance of reproduction from the ancestral seas. The tetrapods that developed the amniotic egg were no longer required to return to water to reproduce. ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________1 | Page