Animal Kingdom: Symmetry, Traits & Development of Sponges, Nematodes, & Arthropods, Study notes of Biology

Download Animal Kingdom: Symmetry, Traits & Development of Sponges, Nematodes, & Arthropods and more Study notes Biology in PDF only on Docsity! Key Characteristics of Animals - Multicellularity (most have tissues) - Heterotrophic - consume organic compounds for energy - Feeding methods - Internal Digestion (some exceptions here, partially external in some insects) Ancestral States of Animalia: Metazoans - Part of the original eukaryotic lineage that evolved from the unikont groups - Soft-bodied, single cells with flagella tend to congregate into colonies - Monophyletic group - Choanoflagellates are the link between protists and animals Animal Kingdown Break Down: 1. Tissue types (tissues or just cells) 2. Symmetry (balance or similarity of body structures of an organism) - Bilateral, ex. hummingbird - Radial, ex. Jellyfish - Asymmetry, ex. sponge 3. Development 4. Genetics 5. Behaviors Sponges / porifera (still metazoans) - Characteristics - No true tissues - Cell types are not concentrated together to perform one function - The body plan is relatively homogeneous and composed of several cell types - Amorphous or irregular or inconsistent shape - Coanocytic collar cells - 5,500 species - Ostium, Oscula, Choanocytes (collar cells), mesophyll, amoeboid cells - The pore (Ostia) will allow for water to come into the cell, and eventually through the organism by the osculum - Two layers of cells separated by the mesophyll - Spicule which provides bonelike structure - Dispersal - Global dispersal (tropical and arctic extremes) - Larval are planktonic - - Males spawn - Females take in the sperm - “Internal” fertilization - Females release larva which eventually settle on substrate elsewhere - Minimal Predation - Only some fish and sea turtles - Limited nutritional value - Phylogeny - Separated into classes - Demospongangiae (demosponges) - Hexactinellida (glass sponges) - Calcarea (calcareous) - Homoschleromorpha (new class!) - Spicule - - - Thick mesoglea - Large effective swimmers - All marine - predators - Cubozoa: box jellies - - Small, but toxic - Sea wasp - All marine - Move much faster and show greater maneuverability than true jellies - Hydrozoa: hydras and siphonophores - Siphonophores: - - Colonial cells specialize and lose abilities becoming interdependent on other cells - Cells become different parts of multicellular organism essentially - Some cells emit bioluminescent lures - Some cells lose their cnidocytes (or at least their nematocysts) - - Characteristics - Colonial “jellies” - Very small when singular and usually smaller than scyphozoans when colonial - Mostly (not all) marine - Many freshwater hydrae - predator - Dispersal - Capable of asexual (budding) and sexual reproduction especially in colonial siphonophores - Staruozoa: stalked jellyfish “tweeners” - Looks like both jelly and a hydra - Anthozoa - - “Flower animals” - Key Characteristics - Polyp structure - Sessile - Thin mesoglea - Tentacles with cnidocytes - Sea anemones - Tentacles at the oral opening with nematocysts - Hydrostatic skeleton - A skeleton is formed by a fluid-filled compartment within the body (coelom) - Found in soft-bodied animals - No medusa stage - Corals: reef-building organisms - Colonial organisms - Variable morphologies - Dispersal - Mostly clear, tropical, low-nutrient waters - Facilitated the Cambrian explosion, coastal wave break protection (created the intertidal), coastal barrier (prevents coastlines from washing away) - Depths of 0-300 feet - Competitively inferior to algae - Susceptible to disease - Parrotfish help (increase heterogeneity) - Adaptations - Zooxanthellae, symbiosis in cnidarians with a mutualistic relationship - The loss of symbiotic zooxanthellae and/or reduction in photosynthetic pigment in zooxanthellae residing within the corals is termed CORAL BLEACHING Why are Ctenophores not part of this group of Medusozoa? - Biradial symmetry, not radial - Specifically, 8 rows of ciliary combes (ctenes) - Lack nematocysts - Complete digestive system - Have an additional layer between the endo and ecto layers Phylum Platyhelminthes: The Flatworms - Triploblastic (the first group to develop a true mesoderm) - - Aceolomates - Cephalization - Eyespots are present - Other sensors: - Other chemoreceptors, mechanoreceptors, statocysts - Primitive nervous system - But distinct brain (central ganglion) with longitudinal nerve cords - Have a primitive gut - Some small free-living forms lack a gut - Lack an anus but have a mouth that releases digestive juices - One pharyngeal opening - Gastrovascular cavity - Protonephrida - Simple excretory system of network of tubules - The lifestyle of the Flatworm (complex life cycles) - Complex life cycle: - Platyhelminthes (flatworms) around 20,000 species - Annelida, around 16,500 species - Mollusca around 100,000 - Lophophorates - Physiology - Coelomates (internal gut completely lined with mesoderm) - Lophophore - U shaped alimentary canal - Possession of a lophophore: a crown of ciliated tentacles that help gather suspended food particles - Cilia trap these particles and bring them into the mouth, a form of filter-feeding - The animal can withdraw its lophophore if conditions are muddy or if predators threaten - Most possess a true coelom, used as a hydrostatic skeleton and have a “U” shaped digestive system - 4 types: - Phylum Phoronida (phoronid worms) - Phylum bryozoa (“moss animals”) - Phylum Brachiopoda - Phylum Entoprocta Why are Rotifers not considered Lophophorates? - Similar in the way that they have larval forms that show similar origins but cilia moved in the adult forms - They have ciliated mouths but lack some of the qualities necessary - They are pseudocoelomates; have partial guts and lack the U shaped alimentary canal - The complete digestive system in the form of an alimentary canal with mouth and anus Phylum Molluska: (a type of lophotrochozoa) 4 types of Mollusks: 1. Class Polyplacophora - Chitons - Mostly marine herbivores - Many plates 2. Class Gastropoda - Snails and slugs - Aquatic and terrestrial - Largest gastropod class has about 70,000 living species 3. Class Bivalvia - Clams, scallops, oysters, mussels 4. Class Cephalopoda (only one with a closed circulatory system) - Squid and octopus - Exclusively marine Phylum Molluska: (a type of lophotrochozoa) - One of the relatively large animal phyla with around 100,000 living species - Very dissimilar body types - Key Characteristics - Bilateral symmetry - Reduced coelem but complete digestive system (mouth and anus) - Protostomes - Squishy bodies with hard parts - Even the octopus has a beak (hard part) - Hard part produced by a mantle - Distinctive body form - Feeding forms - Filter feeding in bivalves - Grazing in snails and chitons - Hunting in octopus - Calcification - Animals with a true coelem of the shizocoel (protostome) type, usually bearing a shell composed mostly of calcium carbonate and secreted by a mantle - The mantle is always withdrawn at the read to form a mantle cavity, which contains an anus and gills - Dorsal epithelium forms a mantle which secretes a calcaerous shell (s) - Calcium carbonate - A muscular foot used for locomotion and clinging - - Physiology - Shell - Greatly reduced coelem - Complete digestive system - Open circulatory system (except in cephalopods) Class Polyplacophora: Chitons - Around 900 species - Marine - Common in the intertidal zone - Restricted to living on hard substrate, especially rocks - Distinctive shell - 8 overlapping, articulated plates - Girdle acts as a suction cup - Grazers - Adaptation for life in areas with heavy wave action, e.g. rocky intertidal zones Class Gastropoda: - Most diverse groups of animals in form, habitat and habit - Nudibranchs (naked lungs) - Most have head dress which are devices that allow for the transfer of oxygen from water - Most are poisonous - Most of them will inject toxins and sequester those toxins and put them out onto the epidermis areas - Some of these don’t end up forming a shell in their adult forms - Largest molluskan class - Characteristics - Visceral mass sitting atop a muscular foot - 90-180 torsion of visceral mass and nervous system during embryonic development - Operculum, a covering over the shell, to stop things from stealing the shell and to prevent desiccation on land - Body usually undergoes asymmetrical torsion (twisting and coiling). - One piece (Univalve) shell, usually coiled. - Well-developed head, sense organs, and nervous system - Locomotion typically by creeping on a muscular foot - Only molluscan group to invade land - Land snails and slugs - Pulmonate snails (lungs instead of gills) - Land and freshwater - Escargot, ecosystem service, consumptive - Feeding - Band of teeth (radula) used for feeding (missing in the bivalves) - Most species herbivorous - Primitive mollusks and gastropods use a tongue-like radula with embedded teeth to scrape encrusted algae from rock surfaces Class Bivalvia - 10,000 species described - Freshwater and marine (no terrestrial bivalves due to filter feeding) - Advanced excretory organs (nephridia) are present - Some ability to regenerate missing parts after injury - All annelids exhibit Metamerism, a division of the body into numerous similar segments - Bilateral symmetry - Protostomes - True coelem - Mesoderm outside of body wall and outside of digestive system - New body design: hollow tube-within-a-tube - Epidermal, chitonous setae (except leeches) - Fleshy parapodia in some groups Class Sedentaria: - Class Oligochaeta, earthworms: - - Key Characteristics - Only one pair of setae per segment - Primarily freshwater or terrestrial - Poorly developed head - Not a lot of body plan diversity - Complex organ system - Important to soil because their digestive wastes leave behind soil nutrients and their tunnels let air reach plant roots - Not a lot of species diversity - Physiology - Locomation in annelids (controlled separately in each segment): - - Each segment contains a walled-off portion of the body cavity - Muscles parallel to the body axis can shorten segments; these segments swell and anchor into the surrounding sand or soil - Muscles perpendicular to the body axis will lengthen the body segments and cause them to push forward - Nervous system produced rhythmic waves of shortening and waves of lengthening among the segments - Small bristles (setae) may help anchor the shorted segments - Dispersal - Species diversity is low - Earthworms can’t get much better - Earthworm biomass per square is high - Lots of available food because there is always more waste - Bands of space where earthworms are not found - Earthworms need moisture - Major Ecosystem Service - As they eat, they grind up soil and dead matter - Worm castings are high potency fertilizer - Recycling essential nutrients - Moving air deeper into the ground - Allowing aerobic bacteria to invade - Allowing root structured easier access to substrate - Class Hirundinea: Leeches - - Key Characteristics: - Most are freshwater or terrestrial - Defining characteristic is a posterior sucker - Ectoparasitic (outside of the host), most commonly on the blood of vertebrates - Leeches have degernerate anatomy: fewer sense organs, fewer segments, etc. - 25% nonparasitic predators - Physiology - Like many parasites, leeches have reduced complexity: - Sensory systems - Digestive systems - Possibly a trade-off for specializations for parasitism - Teeth and suckers - Three jaws inside the mouth caused painless “Y” incision mark on host - Hirudin anticoagulant promotes blood flow, allowing leech to feed for longer - An anticoagulant that keeps the wount open so leeches can feed - Anterior and posterior suckers allow leech to attach to host on both sides but only feed on one side - 32 segments, each with its own “brain” Comparing Lophotrochozoans, Ecdysozoans, and Roundworms - Lophotrochozoans: - Segmented worms - chiton - Ecdysozoans: - segmented arthropods - chiton - Roundworms (not segmented) - chiton Ecdysozoans: - A bilateral, protostome that molts - The sister protostome to lophotrochozoan - Includes arthropods and nematodes - Not all ecdysozoans have a chitonous exoskeleton, because roundworms (nematodes)only have chiton on their eggs; not their body - Key Characteristics - Three layered cuticle composed of organic material, which is periodically moltedas the animal grows - The process of molting is called ecdysis - Lack locomotory cilia/flagella, produced mostly amoeboid sperm - Their embryos do not undergo spiral cleavage as in most other protostomes (lophotrochozoans) - Physiology - Molting regulation - Hormone ecdysone; as the levels drop, molting occurs - Amoeboid sperm - Powered by cytoskeletal elements - Tend to require some sort of water to move easily or through some direct course injection (using female bodily fluids to move around) - Extension of pseudopodia like in amoeboid protists - Consists of: - Nematodes, Roundworms - Key Characteristics: - Many free-living species - Vary insize - Lack a circulatory system - Complete digestive tract - Parasites of animals and plants - Hookworm - Heartworm - trichinella - Physiology - Cuticles are a type of exoskeleton - Barrier between animal and environment - An extracellular matrix - Composedof small proteins but predominantly of small collagen- like proteins that are extensively crosslinked - Estimated 8,000 species - Most are generally venomous and can inflict painful bites, injecting their venomthrough pincer-like appendages known as forcipules - Have a varying number of legs, ranging from 30 to 354 - Have an odd number of pairs of legs - Therefore, no centipede has exactly 100 legs - Predominantly carnivorous and predatory - Phylum Arthropoda: Crustaceans - Key Characteristics: - Crabs, lobsters, crayfish, shrimps, prawns, krill, woodlice, and barnacles - Paraphyletic - 67,000 species described, all ranging in size - Like other arthropods, crustaceans have a chitinous exoskeleton, which they molt to grow - Distinguished from other groups of arthropods by the possession of biramous (two-parted) limbs, and by their larval forms - Physiology - The main body cavity is an open circulatory system, where blood is pumped into the hemocoel by a heart located near the dorsum - The alimentary canal consists of a straight tube that often has a gizzard-like “gastric mill” for grinding food and a pair of digestive glands that absorb food; this structure goes into a spiral format - Body grouped into 3 regions (the segments) - The head - The thorax - The abdomen - The head and thorax may be fused together to form a cephalothorax, which may be covered by a single large carapace (structure) - The crustacean body is protected by the hard exoskeleton, which must be molted for the animal to grow. Various parts of the exoskeleton may be fused together - Each body segment can bear a pair of appendages - The segments of the head, include two pairs of antennae, the mandibles, and maxixllae - The thoracic segments bear legs, which may be specialized as pereiopods (walking legs) and maxillipeds (feeding legs) - The abdomen bears pleopods, and ends in a telson, which bears the anus, and is often flanked by uropods to form a tail fan - Crustacean appendages are typically biramous, meaning they are divided into two parts; this includes the second pair of antennae, but not the first which is usually uniramous - Phylogeny - Malacostraca: crabs, lobsters, shrimp - Ostracoda: ostracods - Maxillopoda: barnacles and copopods - Branchiopoda: fairy shrimp, daphnia - Dispersal - Most crustaceans are free-living aquatic animals - Some are terrestrial (woodlice, pill bugs) - Some are parasitic (rhizocephala,fish lice, tongue worms) - Some are sessile (barnacles) - Phylum Anthropoda: Insects (hexapoda) - 6 legged arthropods - Phylogeny - First group to crawl out of the ocean was the ancestor of crustacea and terrestrial arthropods (and fossil evidence suggests it looked like a modern chelicerate, the spider group) - That group gave rise to terrestrial forms including Myriapoda, Chelicerata and Hexapoda, but its likely there were multiple land colonization events - Hexapoda maintains close genetic similarity to marine crustaceans and may have been a more “recent” land- colonization event - Physiology - Unique system in insects - Internal system - Highly branched air-filled tubes called trachea - Branch throughout the insect’s body to reduce the diffusion distance - Spiracles: openings for gas exchange on the exterior surface of the animal - Malpighian Tubules - Excretory and osmoregulatory system adapted to land - Production and removal of urea in the form of urine - Retention of water if insect body is dehydrated - Not found in all insects - Found in some myriapods and arachnids but may be the result of convergent evolution - Adaptations of tubules - Holds lumnescent compounds - Sequesters or filters toxins - Dispersal - Over 1 million species - First animals to evolve flight - Extremely successful in transition to land - Most are terrestrial - Some aquatic for part of or all their lifecycle - Few marine insects - 2 ways of distinguishing between insects - Winged (pterygota) vs. Wingless (apterygota) - Wingless: - Relatives to insects: silverfish and springtails - Simple development: juveniles look like adults once hatched from egg - Winged: - First evolves in hexapods - Important pollinators and predators - Complex systematics (28 orders) - Complex development - Larval forms don’t look like miniature adults - Numerous instars (stages) - 3 groups 1. Cannot fold wings against the body - Odontata: - Dragonflies and damselflies - Aquatic larvae that metamorphose out of the water - predators 2. Can fold wings but incomplete metamorphosis - Orthopters (grasshoppers, crickets, roaches, walking sticks) - Isoptera (termites) - Homoptera (aphigs) - Dermaptera (earwigs) 3. Can fold wings and undergo complete metamorphosis - Most of the winged insects (about 85%) - 4. Asteroidea - 5. Crinoidea - Class Crinoidea: - Sea lilies and feather stars - Mostly sessile animals - Filter feeding lifestyle - Feeding Mechanism in Crinoids - Pinnules and tube feet act as adhesive filter fiber - Dispersal - Only 80 extant species of crinoids (were more abundant as shown by the diversity found in the fossil record) - Most species are extinct (shallow water to 9,000 feet - can basically live anywhere) - Echinozoa - Key Characteristics - A subphylum of free-living echinodermsin which the body is essentially globoid with meriodional symmetry - Meridian lines down the body - They lack arms, brachioles, and other appendages and do not at any time exhibit pinnate structure. - The echinozoa range from the early cambrian to the present day - There are three groups that we will talk about - Echinoidea: sea urchins - Echinoidea: sand dollars - Holothuroidea: sea cucumbers - Physiology - Bilateral development,and some bilateral retention in adult form - Dispersal - All types are found globally in mild and extreme environments as well as shallow and deep environments - Sea Urchins - Regular (radial adults) and irregular (flat, more bilateral adults) in shape - Water vascular system moves from madreporite through the radial canal - Feed through aristotle’s lantern - Used to scrape algae surfaces,as well as biting and chewing prey - Specialized feeding structure around the esophagus - Complex structure is composed of five jaws made up of calcium plates (ossicles),connected by muscles - Used to scrape and capture prey - Sand Dollars - Key Characteristics - Order of the class of urchins - Modified development and different life history traits - Petal-like pattern of sand dollars has five paired rows of pores - Perforations in the endoskeleton through which podia for gas exchange project from the body - Test is covered by a skinof velvet-textured spines which are covered with very small hairs (cilia) - Coordinated movement of the spines enable sand dollars to move across the seabed - Tests of certain species have slits called lunules - Help the animal stay embedded in the sand to stop it from being swept away by an ocean wave - Adaptations in Sand Dollars - The mouth of the sand dollar is located at the bottom of its body at the center of the petal-like pattern - Unlike other urchins, bodies of sand dollars also display secondary bilateral symmetry - The anus of sand dollars is located at the back rather than at the top as in urchins, with many more bilateral features appearing in some species. - Likely a result of sand dollar’s evolution from creatures that originally lived on top of the seabed (epibenthos), like urchins to creatures that burrow underneath it (endobenthos) - Sea Cucumbers - Key Characteristics - Mobile or burrowing - World-wide distribution with the most species in the south pacific ocean - Feeding structure folds out and facilitates filter-feeding, usually from a sandy burrow - Endoskeleton has calcified structures that are usually reduced to isolated microscopic ossicles (or sclerites) joined by connective tissue - In some species, these can sometimes be enlarged to flattened plates, forming an armor. In pelagic species the skeleton is absent and there is no calcerous ring. - Special Sea Cucumber Skills - Ocean Vacuum - Some species move along sand picking up and filtering sand - Defecate very high pH sand (basic sand defecations) - Considered beneficial in areas experiencing acidification - Evisceration - Organs covered in a strong epoxy - Must regenerate organs after evisceration event - Echinodermata (Stars) - Class Asteroidea: - Key Characteristics - Sea stars - Thick, triangular shaped arms that are typically their widest at the point of the connection to the central of the body - Tube feet - predators - Physiology: Feeding in Sea Stars - Water vascular tube feet pry open shells with little energy expenditure - Everts stomach onto or into prey - Secretes digestive enzymes - Digested material reabsorbed by the stomach into body - Pycnopodia: Sunflower Stars - 24 arms - Up to 15,000 tube feet - Very fast (1 meter per minute) - Still uses water vascular system to move - Tube feet become stiff when water is pushed into them, allowing the sea star to move on a conveyer belt-like rotation of feet - Crown of Thorn Sea Stars - Poisonous - Large and fast - Coral eaters - Apex predatorys in coral reef systems - Extremely fecund mass spawners - Class Ophiuroidea (Brittle Stars and Basket Stars) - Key Characteristics - Thinner, whip-like arms with clear attachment point to central disc - One opening (mouth and anus) - Madreporite on bottom of central disc (by mouth) - Movement not reliant on water vascular system - Benthic - Epizoic species too - Often occur in aggregates - Dispersal: greater than we thought - Many marine systems but often deep - Very diverse in deep habitats - Adapted to deep habitats - Brittle Stars have rapid movement and urchin-like adaptations - Evolve large body size, especially in vertebrates - 4 key characteristics of chordata - Notochord: a cartilaginous rod that runs underneath the nerve cord,supporting it - A dorsal hollow nerve cord which lies dorsally to the notochord and connects the brain to lateral muscles - Pharyngeal slits allow water to enter mouth and pass out of body - Post-anal tail - Urochordata: Tunicates (sea squirts) - How is a tunicate a chordate? - Larval form has a true notochord, dorsal hollow nerve cord, pharynx with slits and apost-anal tail - Larval form is also bilateral, deuterostomic and shows v- shaped muscle segments - Evolved so that adult form lost much of these in the development (not adaptive when sessile) - Physiology: adult tunicate anatomy - Bodies are convered by a tunic - Sack-like body with two siphons - Enlarged pharynx = pharyngeal basket - Suspension feeders - Shared with protostomes - Highly modified because the traits that are reduced were not adaptive for their lifestyle: sessile adult forms - Dispersal - Global: polar to tropic oceans - They can be found floating in the ocean water or attached to rocks, docks, ship hulls and other hard surfaces, usually in the pelagic zone of the water - Larval dispersal is capable of free-swimming but also planktonic so larval moves with ocean currents and does not require energy to stay in the ocean currents for a long time - Vertebrates - The vertebrate ancestor - An estuarine species - A lineage of chordates led to the vertebrates - Evolved during the cambrian, 500 million years ago - Evolution of a skeleton and a more complex nervous system - Evolution of the jaw and other features - Vertebrates start out as a head and a tail - Mutations in the head bones - Specialization in the jaw bones - Specialization in the “neck” and fin connections - Cranium breaks into several plates - Head bones mostly give rise to everything above the hip in tetrapods - Dispersal - Almost every niche - No photosynthesis - And every location (air, land and sea) - Each vertebrate groups is well-adapted to its habitat and niche - What makes a vertebrate? - Endoskeleton - Chordates with a spinal column - The chordate 4 - A backbone with vertebrae - Neural crest - Teeth - Paired appendages - A horizontal semicircular canal of the inner ear - Physiological and cellular anatomical characteristics - Hox genes - genes 2 or more sets - The myelin sheaths of neurons - An adaptive immune system that uses V(D)J recombination - As well as an innate (has both) - Fish - Agnatha: Jawless Fish - Sister taxon of gnathostoma - Hagfish and lampreys - Defined by their teeth and suction - Mostly scavengers - Some parasitic - Gnathastomes: - Assumed that they evolved from ancestors that already possessed a pair of pectoral and pelvic fins - Chondrichthyes: cartilaginous fish - Sharks, rays and skates - Show five chordate synapomorphies - Pharyngeal slit - Dorsal nerve cord - Notochord - Endostyle - Post-anal tail - A series of sensory organs (electroreceptors) that are arranged as a network pores filled with jelly near the eyes, ears, mouth and nose - Ampullae of lorenzini - No swim bladder - Must constantly swim to move water over gills - Buccal pumping - And to prevent sinking - More information on Sharks - Skeleton composed of cartilage - Only true bone is teeth and scales in some species - Increased mobility - No armor as in the placoderms - Skin made of a matrix of tiny, hard, tooth-like structures called dermal denticles or placoid scales - Fins (2 pair) - Pectoral and pelvic - Osteichthyes: Bony fish - Ray-finned fish (actinopterygians) - Key Characteristics - Fins are webs of skin supported by bony or horny spines (rays) - Rays attach directly to the proximal or basal skeleton elements, the radials - Represent the line or connection between these fins and the internal skeleton - Actinopterygians dominate the vertebrates - Comprise nearly 99% of the over 30,000 species of fish - Ubiquitous in freshwater and marine environments - Huge size range - Mostly (95%) are teleosts - Physiology - A buoyancy organ - Neutral buoyancy - Also aids in hearing underwater and sound generation - Fish regulates the gas level by exchange with the blood