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LUCA, Fish Anatomy, Did you know there is no such thing as a fish, this is…

- - - - General info: Radial symmetry, 2 layers the epidermis and gastrodermis (these layers have different cell positions and sometimes different cell types: mucous gland cell - produces mucous, epithelio-muscle cell - locomotion, interstitial cells - differentiate as eggs or sperm, nutritive enzymatic mucous gland - internal layer/gastrodermis used in digestion in the gastric cavity), you will usually find, there is a jelly-like substance called mesoglea in between the two layers (it forms a hydrostatic skeleton), they have tissue level organisation (true tissue, not true organs/ organ systems), there's a nerve network but no nerve cord, they have cnidocytes (specialised stinging cells that operate when nematocysts are triggered, the cnidocyte lid opens releasing a harpoon to inject venom into the stimuli), have two body forms polyp (like a general anemone shape) or medusa (a general jellyfish shape) (IT IS IMPORTANT TO NOTE THAT ANEMONES AND JELLYFISH CAN HAVE EITHER BODY FORM)
      - Subphyla: Endocnidozoa (parasitic)
        
        Class: Myxozoa (obligate parasites)
        
        Class: Polypodiozoa
      - Subphyla: Anthozoa (don't have a medusa stage)
        
        Class: Hexacorallia (anemones and stony corals)
        
        Can be solitary or colonial, not polymorphic, tentacle number is a multiple of 6 (hexacoral), can have a calcium carbonate skeleton, can be associated with photosynthetic zooxanthellae in tropical/ subtropical waters, can be found in deep water
        
        Class:Octocorallia (soft corals, sea pens, gorgonians)
        
        Colonial, non-polymorphic, octacoral, 8 pinnate (leaf/tree/feather-like) tentacles, coelenteron (internal cavity) is divided into 8, structural internal support by horny chalk produced by mesoglea cells, cnidocytes in both cell layers, predators, poor nematocysts
      - Subphyla: Medusozoa (have a medusa stage)
        
        Class: Scyphozoa (true jellyfish)
        
        ~200 species, marine, well developed mesoglea, gonads in gastrodermis, cnidocytes on both epidermis and gastrodermis, mainly lives in medusa phase, polyp phase can happen but not for long, no velum (extra layer near tentacle), moves via bell contraction, eat plankton, filter feed and some are photosynthetic symbionts. Breed sexually and asexually, fertilised eggs become larval planula and can either grow into the medusa phase (planula to ephyra to medusa) or settle on the ground and metamorphosize into a polyp which undergoes budding to form more polyps and release ephyra (immature medusa) by strobilation
        
        Class: Hydrozoa (fire corals, hydroids, siphonophores)
        
        3.7K species, biphasic (polyp and medusa stage), colonial, tend to be polymorphic and do different functions, gonads in epidermis, cnidocytes only on epidermis and acellular mesoglea. Siphonophores are colonies of hydrozoa made of specialised bodies (zooids) but are still genetically identical, the colony can operate like a single individual eg Portugese Man'O'War which has a pneumatophore filled with gas so it can float, it catches prey with its tentacles and it has a reproductive structure called a gonodendron made of different zooids
        
        Class: Cubozoa (box jellyfish)
        
        Small, ~50 species, marine, tropical, box shaped, has velum, thick cellular mesoglea and gonads are located at the gastrodermis, has up too 24 eyes, has 4 sets of tentacles, one set on each side of the "box", nematocysts deadly as they cause cell membrane collapse and disrupt ion channels, has sensory seeing structures called rhopalia
        
        Class: Staurozoa (stalked jellyfish)
        
        ~50 species, cold water, benthic, attach to floor at medusa stage only, no strobilation
      - Misconceptions
        
        Comb jellyfish (Ctenophores) aren't Cnidaria because they don't have nematocysts, they vary a lot, found in deep sea, ~100 species, have 8 rows of cilia called comb rows for swimming, thick mesoglea between two epithelia, have colloblasts which are adhesive cells on tentacles that catch prey by sticking the prey to the tentacle instead of stinging
        
        Tunicates belong in the Chordata not Cnidaria as it has a notochord in one of its life stages, body is in a tunic, has bilateral symmetry, can be sessile or free living, and can be colonial or solitary, filter feeders, have organs like a heart and digestive system, they have a separate anus
    - - Marine, freshwater and terrestrial, very abundant, microscopic (meiofauna), involved in decomposition, unsegmented, cylindrical, pointed at both ends, have longitudinal muscles and nerve ring round the pharynx
    - - General Info: Spiny skinned, varied ecological roles, ~7300 species and >15K fossils, all marine, radial symmetry (pentamerous), bilateral larvae, no head, calcareous, mesodermal skeleton (spines/tubercles, plates, ossicles (calcareous components that form the skeleton) etc), water vascular system for hydrostatically powered feet, tube feet for locomotion/ feeding, decentralised nervous system (has a net of nerves instead), not good at osmoregulation, found in brackish water
      - Class: Holothuroidea (sea cucumbers)
        
        ~1700 species, pentamerous symmetry and bilateral symmetry, arms incorporated in body, calcareous skeleton reduced, locomotion by tube feet, gas exchange by respiratory tree but drawing water in through the anus and expelling it back out, can discard internal organs (either just the intestines or the whole anterior end) and regrow them using specialised cells
      - Echinoidea (sea urchins)
        
        ~1K species, spherical or secondarily flattened, arms incorporated in body, ossicles fused into skeleton called the test (to see if it can have tubercles and spines), has tube feet and spines for movement and latching to substances, digestive system is a coiled tube that joins mouth (faces down) to anus (faces up), can be grazers, scavengers or carnivorous, have a feeding apparatus called Aristotle's lantern made of 5 jaws made from calcium plates connected by muscle, this is used for scraping algae off rocks and chewing prey, they have light receptors on their feet so they can kind of see
      - Class: Asteroidea (sea stars)
        
        ~1900 species, 5-40 arms with spines on them, the spines may form pincer-like structures (pedicellariae), aboral (side furthest from mouth) usually has anus and madreporite (entry way for water to enter the vascular system and travel through canals to the ampullae connected to the tube feet, water flow and ampullae contractions allow movement, it can also work the other way from the mouth side, this process can be used of O2 and nutrients movement), mouth is downward with suckered tube feet that come from ambulacral grooves for locomotion and maybe gas exchange, disk is less distinct from arms, they have ossicles (small calcareous elements in the dermis that provide rigidity and protection)
      - Crinoidea (sea lillies and feather stars)
        
        Origin from sessile, filter feeding echinoderm ancestors, ~620 extant species, mouth faces up, tube feet are just for feeding (not moving), arms pass food to mouth, 5 arms that tend to be divided
      - Class: Ophiuroidea (brittle star) :
        
        ~2K species, free living, distinct ossified/calcified skeleton, long arms distinct from body used for walking/swimming, mouth on lower surface, small disk shaped central body, large stomach but no anus or gut, tube feet used for suspension feeding (pulling particles from water column to mouth, they put their feet up to catch the particles), can form carpets of brittle stars that can take down larger prey and use muscles for movement
    - - General Information: originated 541 MYA, they have a chitinous exoskeleton, jointed appendages and a segmented body, they are known for variation, adapting and occupying many ecological niches
      - Sub-phylum: Hexapoda (insects)
      - Sub-phylum: Myriapoda (millipedes + centipedes)
      - Sub-phylum: Crustacea (crabs + lobsters) General Info: Has a hard but flexible exoskeleton produced by sclerotization, before molting calcium is deposited in new cuticles, segmented by tagmatization (where segments develop by evolution) , has a head, thorax and abdomen minimum, usually have more segments, each segment has jointed limbs, some have biramous (branched) appendages, gas exchange happens through the surface or gills/ lungs, open circulatory system (the hemolymph isn't always in blood vessels and the heart has holes called ostia that draw in the hemolymph and then pushes it into arteries which lead to tissues and organs and then collect in sinuses that lead back to the gills then to the pericardial cavity then to the heart), true tissue/ organs
        
        Superclass: Allotriocarida
        
        Class: Remipedia
        
        20 species. Not primitive but has primitive characteristics, lacks tagmosis (made of repetitive segments and doesn't have a distinct thorax and abdomen, has paddle-like appendages for swimming and but overall not much specialisation, found in cave-like areas
        
        Class: Cephalocarida (horseshoe shrimp)
        
        12 species, 3 eyes, large horseshoe shaped head covered in a cephalic shield made of chitinous and calcified substances, 9 thoracic segments with limbs and 9 abdominal segments but the abdominal segment has no limbs, hermaphrodites, have egg carrier limbs
        
        Superclass: Multicrustacaea
        
        Class: Malacostraca
        
        Has a lot of crustacean species (>29K!) including shrimp, crabs, AMPHIPODS (my shayla) and lobsters, usually segmented, have head, thorax and abdomen. Hoplocarida/ mantis shrimps have the basic pattern, Isopoda, Amphipoda and Mysida have brood pouches to store eggs, Eucarida (crabs and lobsters) have a cephalothorax (a more developed segment) covered by a carapace
        
        Class: Copepoda
        
        9K species, free living, usually plankton, some parasitic, can swim slowly by using mouthparts or can move by a sequence of jumps and breaks by thorax appendages, feed on phytoplankton by maxillae
        
        Class: Thecostraca (mainly barnacles)
        
        Sessile (immobile) adults with a calcified shell, feed using cirri, by adulthood has a reduced first antennae and no second antennae and a reduced abdomen, is mobile at larval stages (nauplius and cypris) then become adults anchored to substrates
        
        Superclass: Oligostraca
        
        Class: Ostracoda
        
        Bilaterally symmetrical, has a carapace that is shaped like a bivalve shell, around 1mm, mainly a head, body isn't clearly segmented and is reduced and sac-like, 2 pairs of well developed antennae for swimming and first pair of thoracic limbs for walking, can be benthic, planktonic or marine
      - Sub-phylum: Chelicerata (spiders + scorpions)
        
        Class: Merostomata
        
        Order: Xiphosura
        
        Mistaken for crustaceans as they are horseshoe crabs, but are closely related to arachnids, they have a horseshoe shaped carapace and a long tail and are benthic in shallow water
        
        Class: Pycnogonida (sea spiders)
        
        Marine, benthic, has cephalosoma (front part made of head, eyes and first pair of legs) then a trunk of 4 pairs of legs, carnivorous (prey= sponges, cnidarians and bryozoans), size varies from ~1cm to 1m, when mating fertilized eggs are transferred to the males ovigers (appendages) where cement glands in their legs package the eggs
    - - ~30K species, some free living, some parasitic, bilateral symmetry, dorso-ventrally flattened, one gut opening, feed on animal tissue (scavenge, parasite or predator), hermaphrodites, move by muscle contraction or ciliary gliding and can regenerate well
    - - Superclass: Aplacophora (they lack a true shell and are worm-like)
        
        Class: Solenogastres (aka Neomeniomorpha)
        
        300 valid species, shell-less worm molluscs, narrow foot lacking intrinsic musculature, mantle covered in chitinous cuticles and calcareous sclerites (spines), has a radula and can be predatory (hunt anemones)
        
        Class: Caudofoveata (aka Chaetodermomorpha)
      - Class: Scaphopoda (tusk shells)
        
        Size varies from a few mm to 10 cm in length, shell is tubular and conical but also cylindrical as its open at both ends, it lives in-faunally (face down) in the sediment feeding off microorganisms (foraminifera) using captacula (feeding tentacles), head is reduced, no eyes, no gills, gaseous exchange happens through the mantle
      - Class: Gastropoda (snails, slugs/nudibranchs and limpets)
        
        Very diverse over 70K living species, some are marine, some freshwater, some terrestrial, they all have heads with eyes, usually on eye stalks, some have shells, all have a distinct foot, they have a visceral mass and a digestive system, snails experience torsion where their internal organs shift and turn 180 degrees so that the anus is above their head, in some snails there can be a modified lung from the mantle, many have a radula which are teeth surrounding an odontophore, when feeding muscles push the odontophore and radula out to get food and pass it to the oesophagus, the radula and odontophore then return to the radular sac
        
        Awesome facts because I like gastropods, limpets have the hardest biological material used for teeth and BEWARE THE CONE SNAIL it has a chitinous harpoon that it produces from a proboscis to paralyse prey and consume whole :O
      - Class: Cephalopoda (includes squid, octopus, cuttlefish and nautili
        
        Generally have head, tentacles modified from a molluscan foot, radula/beak, cognitively advanced, size varies from 10mm to 14M, nautiloids have external shells while coleoids (squids and octopi) have a reduced internal shell called a gladius, the mantle sucks up the water and passes it over the gills, arms are used to handle prey and they have a closed circulatory system
        
        Squids move by jet propulsion where water is sucked up through the mantle over the gills and then the water is forced through the siphon resulting in movement, during this process the head fins and tentacles splay giving the squid the ability to fly, overall this process helps squid to avoid predators
      - Class: Monoplacophora
        
        Have one plate, were thought to have been extinct by 375 MYA but were found in the 1950s, found in the deep sea, has a foot, mantle with gills and a radula
      - Class: Bivalvia (clams, oysters, mussels, cockles and scallops)
        
        Have paired shells with 2 hinged parts that enclose a laterally compressed body, ~10K extant species, caught for food, harvested for pearls and used in bioengineering, they have bilateral symmetry, they have no head or radula and are filter feeders (water is siphoned over the gills for respiration and feeding and then the ciliary motion of gills passes the feed to the mouth)
      - Class: Polyplacophora (chitons)
        
        Plate-bearing organisms, has a dorsal shell made up of 8 overlapping plates with a mantle/ girdle of scales, broad foot, gills, head, no tentacles, grow up to 30cm, feed with radula (herbivores and detritivores)
      - General Info on Mollusca: Many have a mantle but not always a shell, they are soft bodied, crawl with a muscular foot (some glide), many have head with tentacles and some have a radula for feeding, molluscs are visceral masses containing internal organs, all have hearts, molluscs vary a lot especially in circulation like some have gills, some have different respiratory pigments (hemolymph, hemocyanin or hemoglobin), they adapt to both terrestrial and aquatic environments, evolved 500 MYA
    - - General Information: Bilaterally symmetrical, can be microscopic, can be 3m, hydrostatic skeleton so segments can move independently (muscles contract to shift the fluid resulting in movement), highly developed nervous system for burrowing, feeding varies, can reproduce asexually, sexually and can be gonochoristic (many marine species) and can be hermaphrodites, hard to ID as it's centred around mouth parts
      - Class: Polychaeta
        
        Bristle-like chaetae project from parapodia (appendages) on each segment, pre-segmental prostomium and peristomium make the head, then there's segments and the last one is called a pygidium, each segment has components of all the major body systems except gut, closed circulatory system with different respiratory pigments, poor osmoregulators, respiration happens on surface or gills on segments or just the head
        
        Subclass: Sedentaria
        
        Static/ slow, poor jaw and sensory development, specialised gills or tentacles for filter feeding, includes riftia (a hydrothermal vent worm with no digestive system) and osedax (bone eating zombie worm that eats symbionts that break down bones)
        
        Subclass: Errantia - well developed jaw and sensors, free moving. Includes families Tomopteridae (which has well developed eyes, is transparent, good at swimming and hunts plankton), Nereididae (aka ragworms, slender, segmented, proboscis with jaws, can produce a mucous tube and lives under the floor/sand) and Eunicidae (large, burrow, hard jaws, eversible (can be turned around) pharynx)
        
        Subclass: Echiura (spoon worm)
        
        Unsegmented adults, ventral chaetae, live in burrow
      - Order: Sipuncula (peanut worm) - unsegmented, no setae, mouth with tentacles
      - Class: Clitellata
        
        Has a collar, forms a reproductive cocoon, no parapodia, less developed head
        
        I REFUSE TO PUT A REAL PHOTO AS IT IS AN EARTHWORM (I AM SCARED OF EARTHWORMS) TAKE SHELBY INSTEAD
    - - 22 marine species, 1mm-40cm, bilateral symmetry, not dorsoventrally flattened, has prosoma (mouth) which is bulbous and covered with spines, then there's a muscular trunk covered in a chitin cuticle which moults, they burrow extending the prosoma and gripping mud with spines and withdrawing the prosoma in the trunk
    - - General info: 1300 species, unsegmented, flattened, carnivorous, separate mouth and anus, proboscis is separate to gut, ciliated outer surface, moves by muscles, separate sexes, gonads repeat on segments, can reproduce sexually and asexually (fragmentation), closed circulatory system, muscles circulate fluid around the body
    - - About sponges
        
        Has pores are the oldest, simplest metazoans, found all over the ocean, can be over 100 years old, can be 3.5M, larvae can move but adult sponges are sessile aside from the filter feeding flagella, no true tissues or organs, made of differentiated cells, lack symmetry, cell layers separated by mesohyl (elastic matrix of collagen and fibres), shaped like a bag with one open end called the osculum, on the interior of the sponge (the choanoderm) there are cells unique to sponges called choanocytes (cells unique to sponges that have flagella to draw water into the atrium so filter feeding can take place and the water then leaves through the osculum while food moves from choanocyte chambers to the mesohyl layer), mainly marine, asexual (budding), sexual reproduction produces larvae, no nervous system, outer layer (pinacoderm) is made by plate-like cells called pinacocytes, porocytes are cells through the layer with holes called ostium which allows water in the spongocoel/ atrium for filter feeding, amebocytes are in the layer and transport nutrients, cells like sclerocytes and spongocytes make skeletal substances like spicules (vary in size - megascleres or microscleres - can be siliceous or calcareous) and spongin (a type of collagen) to form a skeleton-like structure, oocytes (egg cells for reproduction) are also present, the cells can be separated and reform into the original structure, food for sponges includes bacteria, viruses and unicellular algae
        
        Sponge body plans
        
        Syconoid - thick body wall, pores long forming canals with choanocytes lining the canals
        
        Leuconoid - masses of tissues, many canals, chambers lined with choanocytes
        
        Asconoid - tube with pores, choanocytes in the spongocoel
        
        Other individuals: sponges form microbiomes for other species like bacteria, archaea and other unicellular organisms, sponges contain bioactive compounds, medicines have been made from sponges, the symbiosis with bacteria and fungi etc produce antioxidant and anti aging compounds used in cosmetics
      - Class: Calcarea (calcareous sponges)
        
        Calcifying sponges, make up 8.5% of living sponges, ~800 species, calcareous spicules, 2-4 pointed spicules, can be any of the 3 body plans above, small bodied, live in shallow water.
      - Class: Homoscleromorpha (encrusting sponges)
        
        1.5% of sponges (130 species), spicules silicon dioxide with lower layer disposition of calcite/aragonite, only leuconoid, associated with coral and hard surfaces
      - Class: Demospongiae (demo sponges)
        
        Diverse, make up 83% of sponge species (~7600), 268 freshwater species, silicon dioxide spicules, spongin skeleton, mainly leuconoid, can be carnivorous, have symbiotic relationships with algae/bacteria
      - Class: Hexactinellida (glass sponges)
        
        7% of sponge species (698 species), deep water, silicon dioxide spicules with 6 points, can be syconoid or leuconoid, most of the soft tissue is a syncytial layer (a cell with lots of nuclei formed by cells being so close together they just merge to the point where its a tonne of nuclei in a lot of cytoplasm
    - - Subphylum: Craniata - Contains vertebrata can fish, have cephalisation and bone cartilage, can lack vertebrae
        
        Superclass: Petromyzontomorphi - lampreys, originated from Carboniferous period, still alive, 38 extant species in one class called Petromyzontida, has functional eyes, cerebellum, separate ventral and dorsal roots of the spinal nerve (a vertebrate feature), separate olfactory (sensory system related to smell) and respiratory pathways, some freshwater species are parasites, all anadromous (move upstream for spawning) species are parasites, eel-like, no scales, no jaws, no stomach, tongue has keratinous replaceable teeth, produce pathogen specific substances, don't produce mucous, have 1 or 2 dorsal fins and a caudal fin, have a sub-terminal mouth, have terminal spawning, larvae (ammocoetes), have pineal (light detecting) organ, eyes and neuromasts (small epithelial receptor organs), have 7 gill openings, eat by rasping and sucking
        
        Superclass: Conodonta - was the first superclass to form, went extinct in Triassic period
        
        Superclass: Gnathostomata - the only superclass of fish with jaws (advantageous as it provides protection, more diverse prey which increases size and reduces armour which increases mobility), diversity increased in the Cretaceous period, ancestors unknown, could be Thelodonts (scale-like teeth, stomach, broad based pectoral fins) or Osteostracomorphs (ossified bones around the eyes, cellular bone, slit shaped gill openings, paired fins, 2 dorsal fins and an epicercal tail)
        
        Class: Chondricthyes - originated from Silurian period, 970 living species, calcified endoskeleton cartilage (NOT BONY), pelvic claspers, tend to be predators, dominated ancient seas
        
        Subclass: Elasmobranchii - 5-7 gill openings, dermal, placoid scales, replacement dentition (could be from placoid scales), upper jaw not fused with cranium, ribs, spiracle (outer orifice ring with tube that connects outer snout to buccal mass)
        
        Division: Neoselachii - overhanging mouth (jaw modifications), calcified vertebral centra (disk-shaped bones) replace unconstricted notochord, basal (bottom) fin supports (fused, flexible, horned rays support fin), sexual dimorphism and internal fertilisation, electroreception (sense electricity in environment), oil accumulation for buoyancy, carnivores, can be apex predators, scavengers, plankton feeders, nocturnal feeders, they tend to have a strong bite due to an underslung jaw, teeth pierce, slice and crush, some sharks use their tailfin to stun prey, some rays stun prey using electricity, manta rays have cephalic horns for guiding, some have suction abilities and sometimes the palatoquadrate (upper jaw) can protrude to improve bite strength eg goblin sharks and great white sharks, high olfactory sensitivity, good vision, mechanoreception (detects water displacement), acoustic sensitivity, big brain, reproduce at older age, low fecundity (not many offspring), produce large precocial/mobile young, high energy cost for females, nutrition gained from yolk sac whether its oviparous or viviparous, extra nutrients can be obtained by the mother by eating unfertilized eggs or embryos, or from the placenta or uterine secretions
        
        Subdivision: Selachii - mainly sharks, 403 species, lateral gill slits, pectoral fin isn't attached to head, has an anal fin, has small lateral spiracles, 8 orders, size varies a lot can be 17cm can be 12M, live in shallow temperate or tropical water, mainly coastal, live in shallow water usually outside of any extreme conditions, buoyant (no gas bladder, light skeleton so muscles spread out so it is less dense, oil-filled liver (can't be compressed), heterocercal tail (upper lobe is stiffer for lift), pectoral fins to adjust), swim using undulations, have pacoid scales to reduce turbulence, drag and noise for stealth, mobile, move worldwide, can be local, coastal or oceanic, home range increases with age, low metabolic rate, low food need, low aerobic scope (maximal exercise), vary based on activity, grows slow, long life span
        
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        Subdivision: Batoidea mainly rays, 534 species, ventral (under) gill slits, pectoral fin attached to head, no anal fin, large dorsal spiracles, 5 orders
        
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        Subclass: Holocephali (chimeras) - deep water, gill chamber forward, no spiracle, 1 opercular opening covering 4 gill openings, upper jaw fused to cranium (can't protrude), teeth grow continuously and can't be replaced, naked skin, claspers on head, also have pelvic claspers, venomous spine in front of dorsal fin, no stomach, no ribs, diphycercal tail (pointed)
        
        Class: Acanthodii - originated in Silurian period, extinct by Permian period, spiny sharks, small, stout, big head, big eyes, bony spines before fins, cartilaginous skeleton, covered in small scales, water column feeders, streamlined, round body, reduced armour
        
        Class: Placodermi - extinct by late Devonian period, originated from the Silurian period, bony plates cover 30-50% of the body, big jaws, teeth, mouth gaped (linked to craniovertebral (involves skull and spinal column) joint), diverse (200 genera), antiarchs (pectoral fins enclosed in bone-like arms), reduced body armour, no replacement teeth, can't generate suction forces
        
        Class: Sarcopterygii - Originated in Devonian, 8 extant fish, 26.7K extant terrestrial species, cosmoid scales, fleshy lobed fins, enamelled teeth, bony interior skeleton (the endoskeleton got ossified)
        
        Subclass: Coelacanthimorpha - Originated in Devonian, popular in Triassic, 2 living species, 3 lobed tail supported by hollow spine, unconstricted ossified notochord, double gular plate, spiny dorsal fin, cranio-vertebral joint
        
        Subclass: Dipnotetrapodomorpha
        
        Clade: Tetrapodomorpha - has the infraclass Tetrapoda however this group is of large predatory fish with symmetrical tails, peaked in late Devonian, extinct in Permian except Tetrapods, has a robust limb skeleton (hip, shoulder girdles and rotational shoulders), can be up to 6M, dorsally placed eyes, one pair of external nostrils, choana (excurrent nostrils moved to palate), might be ambush predators, developed more digit-like elements while sticking to Sarcopterygian features, eyes began to grow larger as it would stick its head above water
        
        Infraclass: Tetrapoda - moving to land has some challenges like a change in gravity, respiration, circulation, digestion, sensory reception, reproduction, pectoral fins and moving in general however the move to land does have its benefits as movement isn't as limiting, marine predators could be avoided but marine animals did still have to feed in the water even though they could catch land prey there was a higher oxygen concentration in the air and its less dense and viscous than water, there is O2 available everywhere in air however, it is hard to keep respiratory surfaces wet in air, gills also clump together in air which reduces surface area, and frequency of breathing increased so surfacing has to happen more frequently and it's easier to expel metabolic waste in water, some organisms use bimodal breathing where you can respire in water and air
        
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        Clade: Dipnomorpha (lungfish) - 6 extant species all freshwater
        
        Class: Actinopterygii - Originated in Silurian, 26.8K extant species, monophyletic (evolved from shared ancestor), no spiracles, no gular/throat plate, can have no scales or can have ganoid, cycloid or ctenoid scales, bony interior skeleton (the endoskeleton got ossified)
        
        Subclass: Cladistia (bichirs) - 16 species
        
        Subclass: Chondrostei (sturgeons and paddelfishes) - 27 species
        
        Subclass: Neopterygii - dorsal fin and anal fin have the same number of fin rays, every ray, fin and spine have a set of turgid walls,
        
        Division: Teleostei - complete bony fish, has the rest of the species (26.8K), mobile premaxilla, neural arches (neural arches are the part of the spine that arch over and enclose the dorsal nerve cord) on dorsal side of tail base (the neural arches are fused to the uroneural bones), ventral pharyngeal toothplates are unpaired and skull bones are arranged in a particular way. Due to the high amount of species in this group there are a lot of variances including number of ossified vertebrae (20-80), vertebral accessories, bones in skull and ray/tail, pairs of fin rays and scale type (cycloid or ctenoid)
        
        Subdivision: Elopomorpha (gulper/swallower eels, ladyfishes, tarpons, bonefishes) - 804 species, has ancestral features like gular plate, ganoid scales, bony, snapping jaw, they produce leptocephalus (flat/ ribbon-like) larvae
        
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        Subdivision: Osteoglossomorpha - 220 species, bony tongue (teeth on tongue and roof of mouth which grinds prey), tropical and freshwater, in a lot of continents, elephant fishes and aba produce and detect electricity
        
        Subdivision: Otocephala - 8344 species, is otophysic (has a connection from gas bladder to ear), good hearing
        
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        Subdivision: Euteleostei - 17422 species
        
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        Order: Amiiformes (bowfin) - 1 species, asymmetrical tail, undulation of dorsal fin
        
        Order: Lepisosteiformes (gars) - 7 species, heterocercal tail, use gas bladder as lung
        
        Superclass: Myxinomorphi - hagfish, THE ONLY NON VERTEBRATE OF THE SUPERCLASSES, originated from Carboniferous period, still alive, has one class called Myxini where there are 70 species, lives in temperate (no extreme temperatures) conditions, lives below 330m in ocean, seawater only as it's isosmotic (has the same osmotic pressure), lacks vertebrae, no true eyes, burrow, hypoxia tolerant, predates benthic invertebrates and scavenges by latching onto carcasses, has 70-200 pairs of slime glands, it produces carbohydrates that when exposed to water turn into slime, it is used to escape predators and ties itself into a knot to get rid of any mucous/slime stuck to it or to feed off carcasses, eel-like, no scales, no jaws, no stomach, tongue has keratinous replaceable teeth, produce pathogen specific substances, have continuous caudal fins, terminal mouth, repeat spawning, direct development from egg, photoreceptors in head and cloacal region, 1-16 gill openings, bite and tear to eat
        
        Superclass: Anaspida - went extinct in Devonian period, is an ostracoderm (bony fish with no jaw that originates from the Ordovician period but was dominant in the Silurian period, have bony shield over head and thorax, some small, some over a metre long, has cellular bone, dentine-like tissue, paired limbs, intricate sensory line systems, complex eye muscles and the inner ear has 2 semi-circular canals), small (<15 cm), fusiform (torpedo shaped), laterally compressed, benthic, parasitic or detritus feeders, no shield, overlapping tuberculate (small, resemble spikes) scales, fin-like projections, muscles and internal skeleton for manoeuvrability
        
        Superclass: Thelodonti - went extinct in Devonian period, is an ostracoderm (bony fish with no jaw that originates from the Ordovician period but was dominant in the Silurian period, have bony shield over head and thorax, some small, some over a metre long, has cellular bone, dentine-like tissue, paired limbs, intricate sensory line systems, complex eye muscles and the inner ear has 2 semi-circular canals), small (10-20cm), fusiform, depressed/concave, large head, horizontal mouth, hypocercal tail (upper lobe is smaller than lower lobe), dorsal and anal fins, benthic, forktail form so was supra-benthic (mainly benthic but will go up every now and then), covered with scale-like denticles (small teeth-like projections), stomach, lateral line (sensory system that detects water movement/flow)
        
        Superclass: Osteostracomorphi - went extinct in Devonian period, is an ostracoderm (bony fish with no jaw that originates from the Ordovician period but was dominant in the Silurian period, have bony shield over head and thorax, some small, some over a metre long, has cellular bone, dentine-like tissue, paired limbs, intricate sensory line systems, complex eye muscles and the inner ear has 2 semi-circular canals), abundant, diverse, large anterior bony shield with eye, nose and pineal openings, ossification of endoskeleton (bones form inside), epicercal tail (upper lobe larger than lower lobe) body form and paired fins encourage lift, has a complex brain
        
        Superclass: Pteraspidomorphi - went extinct in Devonian period, is an ostracoderm (bony fish with no jaw that originates from the Ordovician period but was dominant in the Silurian period, have bony shield over head and thorax, some small, some over a metre long, has cellular bone, dentine-like tissue, paired limbs, intricate sensory line systems, complex eye muscles and the inner ear has 2 semi-circular canals), mainly small 10-20cm some grow to 1.5M, benthic filter feeders, have reduced armour, narrower head shield and lateral projections (features that extend out at the sides)
        
        Vertebrata is unknown in the positioning, it is still in debate, some think its a subphylum some think it's under the subphylum Craniata, as there is an overlap in species, vertebrates have vertebrae, neural crest cells (origin of vertebrae skeletal tissue), dermal bone and usually paired appendages, cephalisation (evolution where nerves and sensory structures shift towards the head resulting in change of head size), a skull, closed circulation and red blood cells. There are 55K extant species of vertebrates, 27K of these are tetrapods (0.5K of those marine) and 28K are fish (16K of those are marine). The focus of vertebrates is bone, many fish are have cartilage instead (tough, semi transparent, elastic, flexible, glycoprotein strengthened by collagen) however the bone we know is a mineralised skeleton which can be external (derma bone) or internal (endochondral) which is derived from cartilage, these can be used as support for muscles to attach to for efficient locomotion, it can be used for protection and storing chemicals for metabolism
      - Subphylum: Cephalochordata (lancelets)
      - Subphylum: Urochordata (tunicates)
- - - - Kappaphycus /Eucheuma (40.7%)
      - Gracilaria (13.8%)
      - Undaria (6.9%)
      - Porphyra/ Pyropia (6.8%)
      - Sargassum (0.6%)
      - Saccharina/Laminaria (27.3%)
  - - - Opposite
      - Alternate
      - Whorled
      - Dichotomous (evenly forked)
      - Irregular