group 4 zoo

• The Phylum Annelida includes a large number of species that are often referred to as "segmented worms"

  
• Annelids


  Around 16,500 species that can be found in marine, freshwater, and terrestrial habitats, ranging from less than a millimeter to several meters in size
• Etymology of Annelida


  From the Latin: Annellus, a little ring, referring to the many body segments that compose the body of a segmented worm

  
• Classification of Phylum Annelida

  • Polychaeta
  • Oligochaeta
  • Hirudinea
• Annelids


  • Have a segmented body plan wherein the internal and external morphological features are repeated in each body segment
  • Exhibit bilateral symmetry and are worm-like in overall morphology
  • Have a primitive bilobed brain formed by two cerebral ganglia (bundles of nerve cells)
• Characteristics of Annelida


  • Exhibit organ system level organization
  • Have a segmented body
  • Respire through their body surface
  • Have nephridia as excretory organs that filter fluid from the coelom

  
• Segmentation


  • Allows movement with maximum protection
  • Each segment contains repetition of excretory and movement organs
  • Each segment is separated from each other by a septum
  • Provides an evolutionary framework to build upon
• Other major phyla with segmentation are Arthropoda and Chordata
• Characteristics of Annelida


  • Have a well-developed circulatory and digestive system
  • Their body contains hemoglobin, which gives them a red color
  • Most are hermaphrodite, reproducing both sexually and asexually
  • Regeneration is a very common characteristic

  
• The Annelids are coelomate and triploblastic

  
• Important Characteristics of Annelida

  • Epidermal, chitonous setae (except leeches)
  • Setae are arranged in bundles on paddle-like appendages called parapodia (in polychaetes)

  
• Annelida has 3 Major Classes

  • Polychaeta
  • Oligochaeta
  • Hirudinea
• Class Polychaeta


  • All live in the ocean
  • Have many setae
  • Contains 2/3 of all known Annelids
  • Common species are clamworms, sandworms, and lugworms
  • Have a well-developed head with specialized sense organs

  
• Movement of Polychaeta


  • Each segment has paired parapodia for swimming/crawling
  • May burrow, using peristalsis
• Feeding of Polychaeta


  • Deposit feeders (eat mud, digest organic content)
  • Raptorial predators
  • Herbivores/Scavengers
  • Filter feeders (with mucous net or feeding arms)
• Reproduction of Polychaeta


  • Dioecious - mostly have two sexes: male and female
  • Segmentation allows regeneration
  • Epitoky - posterior (tail) end of worm grows enlarged gonads and eyes, parapodia become modified for swimming, often breaks off and swims away to reproduce

  
• Ecology of Polychaeta


  • Often have effective defense strategies (tubes to hide in, vicious jaws, modified "stinging" setae, mutualistic relationships)
  • Some are a delicacy (Palolo worm)

  
• Class Oligochaeta


  • Live in freshwater, land, ocean
  • Have specialized digestive system to obtain maximum nutrients from detritus
  • Few setae (chitinous hairs)
• Movement of Oligochaeta


  • Must burrow with peristalsis, using circular and longitudinal muscle contractions
  • Use chaetae as anchors
• Feeding of Oligochaeta


  • Deposit feeders (earthworms)
  • Herbivores/scavengers
  • Usually feed on detritus (decaying organic matter)
• Earthworms consume dirt as they burrow, but they do not get nutrients from the dirt. Their nutrients come from decaying plant and animal remains that are in the dirt.
• Reproduction of Oligochaeta


  • Hermaphroditic
  • Worms reproduce by holding the clitellum together and exchanging sperm, clitellum provides mucus for transfer of sperm and creates a cocoon for eggs
• Ecology of Oligochaeta


  • Earthworms are essential soil aerators, mixing the soil with their tunnels
  • Worm feces are great plant food = fertilizer
• Class Hirudinea (Leeches)


  • Mostly freshwater, but some marine and terrestrial species
  • No setae or parapodia
  • Usually have a fixed number of segments (34)
  • Each metamere consists of several annuli

  
• Movement of Hirudinea


  • Have suckers on both ends, move like inchworms
  • Lack septa between metameres, so incapable of moving like Oligochaetes
• Feeding of Hirudinea


  • 3/4 blood-sucking ectoparasites, 1/4 predators
  • 3 Triangular teeth slice skin, proboscis is forced in, along with anticoagulant, blood is sucked through proboscis by pumping of pharynx
• Reproduction of Hirudinea


  • Hermaphroditic
• Ecology of Hirudinea


  • Some are parasitic blood suckers (can be temporary or permanent), many are predators
  • Used medicinally since the 19th century, currently used to increase blood flow following reconstructive surgery
  • Hirudin is a powerful anticoagulant found in the salivary glands of leeches
• "REPTILE" is an egg-bearing vertebrates that has a tough skin with a covering of hard, dry scales. In fact, the term also includes birds, with their covering of feathers.
• Living reptiles include: turtles and tortoises, tuatara, squamates (lizards, amphisbaenians, and snakes), crocodilians (crocodiles, alligators, and caimans), and birds. Crocodilians are more closely related to the birds than to the other reptiles, and together they form a group known as the Archosaura ("ruling reptiles"), which also contains several extinct groups of dinosaurs and pterosaurs (flying reptiles). Birds, then, are warm-blooded reptiles with feathers.

  
• Reptilian classification: Dry skin; unlike the moist skin of amphibians
• Hirudin


  A powerful anticoagulant found in the salivary glands of leeches
• Hirudin is a powerful anticoagulant that is found in the salivary glands of leeches
• Living reptiles include


  • Turtles and tortoises
  • Tuatara
  • Squamates (lizards, amphisbaenians, and snakes)
  • Crocodilians (crocodiles, alligators, and caimans)
  • Birds

  
• Reptiles


  • Dry skin; unlike the moist skin of amphibians makes them vulnerable to dehydration on dry land
  • Reptile scales are made of keratin from the epidermis
  • Reptiles are further distinguished from vertebrates lower on the evolutionary scale by their ability to perform internal fertilization
  • Have few or no glands present in their skin
  • The brains of reptiles are proportionally much smaller than those of similar-sized mammals
  • Reptiles produce amniotic eggs, which differ from those of amphibians

  
• Four orders of reptiles

  • Rhynchocephalia
  • Turtles and Tortoises (Order Chelonia)
  • Lizards and Snakes (Order Squamata)
  • Crocodiles, Alligators, and Gharials (Order Crocodilia)

  
• Rhynchocephalia


  The one surviving species is the tuatara who live on islands off the coast of New Zealand
• Tuatara


  • Their teeth are fused to their jawbones and those on the tip of their upper jaw are modified into a beaklike arrangement
  • Tooth attachment and structure distinguish the tuatara from other reptiles
  • They lack the hemi penis (double penis) unique to squamates
  • They lay eggs, which take about a year to hatch, and have long life spans
  • They share underground burrows with ground-nesting seabirds
• Turtles and Tortoises


  • They are heavily armored reptiles with bony shells that originate from their ribs and cover the top and bottom of their bodies
  • They all lack teeth and instead use a sharp horny "beak" to break up their food
  • The dorsal portion of the shell is the carapace and the ventral portion of the shell is the plastron
  • Turtles (often known as tortoises) occur on the land in freshwater, and in the sea and all turtles are oviparous
  • Females use their hindlimbs to excavate nests in the soil and lay nearly spherical eggs, with some marine species laying up to 100 in a clutch
• Lizards

  • They are the most numerous group and are distinguished by the presence of legs, although limblessness has evolved many times among squamates
  • They have eyelids and external ear openings
  • Most lizards are oviparous; some are ovoviviparous or viviparous
  • Many lizards live on surface substrates and retreat under rocks or logs when necessary