BIOL 110 Freshwater Streams Part 2

[Virtual Presenter] Biome 4 : Freshwater Streams Part II (Morris et al., Ch. 48, 34) Who are the consumers in rivers? BIOLOGY 110Y.

[Audio] 4. Freshwater Stream Also, in rivers / streams, the carbon cycle overlaps with terrestrial surroundings Leaves will enter the stream Some organisms have life stages in both Terrestrial animals will take prey from the stream (and vice-versa) Animal waste / remains may enter water.

[Audio] Freshwater Animals as Indicators of Environmental Disruption One-third of all amphibian species are threatened with extinction. Many amphibian species have narrow environmental tolerances and exchange gases through their skin, making them especially sensitive to environmental disruption..

[Audio] Freshwater Animals as Indicators of Environmental Disruption Habitat destruction, the use of pesticides, and fungal infections have all contributed to amphibian declines These factors, along with invasive species, run off from construction/agriculture/road salt, changes to land use & climate change are changing who is living in our rivers Bioassessment is the identification of living organisms in natural systems to assess if they are "healthy" habitats.

[Audio] Conservation Biology Diminished biodiversity may make communities less productive and less resilient to fires, hurricanes, or other environmental events Lost species mean lost opportunities for the discovery of novel compounds for medical research, or industries like fishing and travel Humans are connected and rely on the land and its inhabitant – biodiversity loss will change the lives of all peoples.

[Audio] See Ch. 34.5 Subphylum Vertebrata (Craniata) All have a cranium enclosing the brain Cranium, and endoskeleton may be made of cartilage or bone Endoskeleton supports body, allows much larger body size! Muscles attach to endoskeleton to allow movement.

[Audio] Endoskeleton permits larger body size without limiting size of internal body cavity (as exoskeletons do) Cartilage skeleton developed prior to bone Bone is stronger than cartilage, and superior for muscle-tobone attachment.

[Audio] Some Early skeleton were most likely made of cartilage, some lower vertebrates still have only cartilage.

[Audio] Endoskeleton of living hagfishes, lampreys, sharks and their kin, and even some "bony" fishes, such as sturgeons, mostly composed of cartilage Perhaps bone evolved, in part, as a means of mineral regulation Phosphorus and calcium are used for many physiological processes.

[Audio] Major Vertebrate Classes Jawless fishes (hagfish, lamprey) Cartilaginous fishes (Sharks, skates, and rays) Bony fishes (Trout) Amphibians (frogs) Reptiles & Birds Mammals.

[Audio] Subphylum Vertebrate (Craniata) A "general" vertebrate physiology is difficult Lots of diversity and different methods for respiration, excretion, feeding, reproduction, etc. Let's talk Teleosts!!.

[Audio] Ray-finned fish fins are supported by bone or spines, connected to skeleton skin over the bone to be "web-like" fin Contrast to lobe-fined fish (left; see Fig.34.30) "fishes".

[Audio] Ray-finned Fishes (class Actinopterygii) → Teleost fish (infraclass Teleostei) (includes salmon, trout, eels, etc.) Make up 96% of all living fishes ; ½ of all vertebrates Found from high altitudes to great depths Large temperature range (-2o C to 44o C) Marine and freshwater Major characteristic of teleosts: specialized scales, fins, and tails allow exceptional mobility changes in jaw structure allow new types of prey to be caught ** just a few specializations of teleosts.

[Audio] Swim bladder filled with air for buoyancy → gas diffuses in to fill bladder → also involved in sensing.

[Audio] Ancestors were covered in heavy, dermal armour Scales are lighter and allow more mobility More easily capture prey, escape predators Teleost scales overlap (reduce drag in water), and grow by adding outer rings.

[Audio] Feeding In general, most fish spend most of their time searching for food (actually, true of most vertebrates) Evolution of jaws meant new types of food became available (not just filter feeding) Most fish are carnivores – feeding on zooplankton, insect larvae, crustaceans, smaller fish – BUT fish (mostly) cannot chew their food! – Chewing would block water flow across gills – Most swallow food whole help!.

Primitive Jaws - No Pucker upper jaw bones upper jaws don't protrude.

[Audio] TeleostJaws. Teleost Jaws.

[Audio] Reproduction: Most fishes are dioecious (separate sexes) with external fertilization and external development Some are ovoviviparous fish that develop in ovarian cavity → embryo develops in egg, within mother until ready to hatch Some sharks are viviparous with some kind of placental attachment to nourish young → embryo develops with placenta inside mother, until live birth Most oviparous pelagic fish lay huge numbers of eggs → eggs laid with no development of embryo inside mother.

[Audio] In Canada, Salmon is king of teleosts! Cultural, economic history of significance Natural stocks continue, but fish farming (aquaculture) has grown in past decades Many implications to conservation of salmon, and surrounding animals.

[Audio] In Canada, Salmon is king of teleosts! Salmon are anadromous Grow up in sea, spawn in freshwater 6 species of Pacific salmon and 1 Atlantic salmon migrates Atlantic salmon makes repeated spawning runs Pacific species spawn once and die Atlantic Salmon.

[Audio] Pacific species of sockeye salmon – Migrates downstream – Roams Pacific for 4 years – Returns to spawn in parents' stream – Young fish are imprinted w/ odour of their stream – May navigate to stream mouth by sensing earth magnetic field or angle of the sun, and then smelling their way home Salmon are endangered by stream degradation from logging, farming, pollution and hydroelectric dams.

[Audio] tetrapods "four-legged vertebrates" "fishes".

[Audio] Bony Fishes to Tetrapods ~the slow crawl onto land~ 3 features unite bony fishes and tetrapod descendants: Bone replaced cartilage during development Lung or swim bladder is present Evolved as an extension of gut Increased vascularization of the air-filled cavity Double circulation directs deoxygenated blood into the lungs and oxygenated blood out to body Have several unique cranial & dental characters ugh, what stinks?.

[Audio] Bony Fishes to Tetrapods ~the slow crawl onto land~ Characteristics adapted for aquatic habitats, made it possible to explore terrestrial habitats: Air-filled cavity functioned as a swim bladder Paired nares (or nostril) used in chemoreception On land, would be used to draw in air through nares Bony elements of paired fins Modified for support and movement underwater On land, would provide same function hey cuz!.

[Audio] Movement Onto Land is perhaps the most dramatic event in animal evolution Animals are composed mostly of water Land represents a relatively dangerous habitat Vascular plants, pulmonate snails, and tracheate arthropods made transition prior to chordates.

[Audio] Adaptations included skull, teeth, pectoral girdle and jointed limbs Tetrapods (vs fish) – Have stronger backbone – Muscles to support the body in air – Muscles to elevate the head – Stronger shoulder and hip girdles – More protective rib cage – Modified ear structure to detect airborne sounds.

tetrapods.

[Audio] Modern Amphibians (Class Amphibia) Diversity >6000 living species in three orders Remain tied to water Eggs must be kept moist Larvae depend on gills for respiration Challenges faced living terrestrially: Thin skin loses water rapidly → need moist habitat Eggs easily dry out, must be shed into water or kept moist – A few brood young.

[Audio] Fig. 34.31. Fig. 34.31.

[Audio] Salamanders (O. Urodela) ~553 living species, primarily in northern temperate regions Most are small, < 15 cm long Burrowing & some aquatic forms may have lost their limbs Carnivorous as both larvae and adults – Feed on worms, small arthropods, and molluscs Breeding Behavior – Most have aquatic larvae and terrestrial adults Aquatic: lay eggs in clusters or stringy masses Terrestrial: lay eggs in small clusters under logs or in soft earth – Terrestrial species undergo direct development.

[Audio] Frogs and Toads (O. Anura) ~5900 species Must live near water source – Reproduction requires water – Skin is water-permeable skin All have a tailed larval stage (tadpole) and tailless, jumping adults (except for 1 species) Eggs of most hatch into tadpoles with a long, finned tail, no legs, internal and external gills and specialized mouthparts for (usually) herbivorous feeding Tadpoles look and act entirely different from adult frogs.

[Audio] amniotes tetrapods "fishes" eggs are adapted to be laid on land.

[Audio] Phylum Mollusca > 90,000 living species / 70,000 fossil species Include snails, slugs, clams, mussels, oysters, squids, octopuses, and nautiluses Still need: Moisture Shelter Calcium in soil Some may be parasites Prominent Mollusc Classes.

[Audio] Molluscs: basic body characteristics Mantle (folds of skin covering viscera) and mantle cavity produces shell in some molluscs houses gills or lungs; surface acts in gas exchange highly modified in some molluscs.

[Audio] Molluscs: basic body characteristics Head-foot region - many important functions Well-developed head (mostly…) Radula (rough ribbon-like organ) Foot used for movement →adhesion, extend hydraulically, burrow into mud/sand, finlike for swimming.

[Audio] Gastropods Largest mollusc class- >70,000 extant sp. Many have shells Tend to be sluggish Shell is one-piece (univalve) May be coiled, or uncoiled Development usually involves: Trochophore stage Veliger stage (shell and foot starts to form) Role in the environment is diverse, includes scrapers of algae, plants (prevent overgrowth), and often prey for many other organisms (birds, mammals, fish, etc.).

[Audio] Coiled shells may be: Right-handed → dextral or Left-handed → sinistral …judged by holding the shell with apex up and aperture facing you! What's THAT?! Tough operculum protects soft snail heads.

[Audio] Gastropods: feeding Radula → rough ribbon-like organ Found in all molluscs, except bivalves Muscles move radula outwards Used for scraping, piercing, tearing, cutting, boring Two main functions: 1. scrape food particles from hard surfaces 2. act as a conveyor belt to move food towards stomach.

[Audio] Gastropods: feeding Well defined head & mouth Radula is a toothy ribbon that is key for collecting food What "food" is, can be variable….

[Audio] Gastropods: feeding Most are herbivores scraping algae off of surfaces foraging for green vegetation (i.e. land snails) Some are scavengers, feeding on dead and decaying organic matter Marine snails: Some are parasites of corals Some are predators Martinell et al., 2010; Palaios Use radula to tear at their prey Bore holes into shells of shelled prey, and a proboscis to feed on soft tissue.

[Audio] Gastropods: Respiration and Reproduction Respiratory organs found in mantle cavity →ctenidia (primitive gill) →secondary gill, or →lungs in some gastropods.

[Audio] Gastropods: Reproduction: dio- or monoecious (hermaphrodite) →Fertilization in water, trochophore within the egg →Shelled eggs may be released to water column or attached to surface, veliger emerge →Terrestrial and some freshwater gastropods fertilize internally, within oviduct →Young snails emerge from eggs but other life stages occur inside egg.

[Audio] Gastropods: Diversity Terrestrial gastropods land "snails" have shells land "slugs" have no shells both are air breathers, and have opening to "lung" visible.

[Audio] Gastropods: Diversity Freshwater snails Numerous species/lineages that have successfully adapted to freshwater Most have shells Some breathe using gills, some surface to breathe air using lungs Important in some cultural cuisines (food)… and human health Some parasites use snails hosts.

[Audio] https://www.invadingspecies.com/invad ers/invertebrates/invasive-snails-2/.

[Audio] Bivalves ~ 9,000 extant sp. Most are marine, also freshwater and brackish water Most are sedentary filter feeders Create water currents using cilia on their specialized gills No defined head No radula Very little cephalization (clustering of nervous tissue toward one end).

[Audio] Bivalves 2 valves held together by a hinge ligament Valves are drawn together by strong adductor muscles Resting state is shell open Fig. 34.14.

[Audio] Bivalve Shell. Bivalve Shell.

[Audio] Umbo is oldest part of the shell, growth occurs an rings Pearls produced when an irritant is lodged between the shell and mantle – Layers of nacre secreted around the foreign material.