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Crustaceans Video: https://www.youtube.com/watch?v=3vENk9QPp4M Crustaceans All Arthropods have: Exoskeleton Jointed legs Source: https://www.thoughtco.com/subphylum-crustacea-crustaceans-1968439 Crustaceans Basics Crustaceans are Arthropods Animal Kingdom Phylum Arthropoda Subphylum Crustacea The name Crustacean comes from crusta meaning “crust” or “hard shelled ones”, due to the hard body armor typical of these animals Most crustaceans live in the ocean and filter feed, scavenge, are predatory, or parasitic However, some live in freshwater and others are terrestrial Known Crustaceans The most well-known crustaceans include: Lobsters Crabs Shrimp Crayfish/Crawfish Crustaceans Physical Characteristics Crustaceans have four body parts: Eyes Antennae Mouthparts Swimmerets Although it is typically classified as three (head, thorax, abdomen) or two (cephalothorax and abdomen) Crustaceans Physical Characteristics (continued) All crustaceans have four antennae (only arthropod to have four antennae) Large Small Crustaceans do not have a heart but rather have an open circulatory system They have compound eyes Crustacean Reproduction Typically reproduce sexually and fertilize externally but they are some species which regularly reproduce asexually Eggs are held in brood chambers attached to the abdomen, or attached to abdominal appendages Most crustaceans have a larvae which is unlike the adult and so must undergo metamorphosis However, crayfish develop directly without a larvae form Crustacean Population There are more than 800 families and over 40,000 species Some species live on land but 99% live in some type of water, either fresh or saltwater Found in all different sizes, from a few inches to 10 feet History Crustaceans first appeared around 600 million years ago Fossils of over 2,000 species have been found Main Crustacean Classes Branchiopods – mostly small, freshwater animals that feed on plankton and detritus Remipedia – blind crustacean found in coastal saline aquifers Cephalocarida – horseshoe shrimp Maxillopoda – include barnacles and copepods (most abundant type of crustacean) Copepoda – fish lice Pentastomida – tongue worms Ostracoda – sometimes known as seed shrimp Malacostraca – includes the most well-known crustaceans Includes lobsters, crabs, crayfish, shrimp, krill, and woodlice Malacostraca Largest and most diverse class of Crustacea with over 20,000 species Typically have a head with 5 fused segments, a thorax, with 8 segments, and an abdomen with six segments Order Isopoda This order includes pill bugs These are the only truly terrestrial crustaceans Order Amphipoda Marine, freshwater, and terrestrial forms Amphipods resemble isopods Order Euphausiacea Contains 90 species Includes planktonic kelp, baleen whales main food source Order Decapoda All Decapods have 5 pairs of walking legs and typically a pair of front pinchers Lobsters Lobsters are cold blooded, meaning their body temperature depends on the temperature of the water Most lobsters are nocturnal Largest lobster ever caught was 44 pounds They may live to be 100 years old Come in a variety of colors and textures Due to its abdominal flexors and shape of its tail, lobsters can dart backward in the water if needed to escape possible predators Image: 22 pound lobster Order Decapoda (continued) Crabs There are about 4,500 different kinds of crabs Crabs have well developed senses that help them find food and stay away from predators Crabs have three sets of jaws which help them crush food into tiny pieces for easy digestion Crayfish Basics Also called crawfish or crawdad, interchangeably Considered close cousins of lobster, crabs, and shrimp Lobster, crab, and shrimp live in salt water Crayfish live in freshwater, in lakes and streams They are found in every continent except Africa and Antarctica More than 230 species live in the US New species are discovered every year Crayfish Facts They are NOT fish Although they breathe with gills, they can stay out of water as long as their gills stay wet Have five pair of legs 4 pair are used for walking One pair is a set of pinchers used to grab things, especially food and for digging Crayfish Growth Their exoskeleton does not grow When they get too big for their shell, they molt and break out of their old shell At this time, they are very vulnerable to predators until their new shell hardens They will molt many times throughout their life They can also regenerate lost body parts Crayfish Diet They hunt for food at night Eat almost anything small - They clean up stream and lake beds - Eat decaying plants and animals Crayfish Sensing Eyes are located on stalks that can move around In front of the two eyes are two sets of feelers or antennae One set is long The other set is short The antennae are covered in tiny hairs which help them touch, taste, and smell Crayfish Reproduction Crayfish lay eggs Females lay the eggs and crawls into a hiding place to protect them When the eggs hatch, they stay stuck to the mother’s tail until ready to swim of their own Crayfish Predators Predators of crayfish include racoons, otters, mink, fish, turtles, some birds, and people Crayfish hide under rocks or burrow into mud They can defend themselves with their claws Can swim backward Shrimp There are over 2,000 different species of shrimp worldwide Range in size from a fraction of an inch to 9 inches long Shrimp are eaten by many animals including many fish, birds, octopi, squid, cuttlefish, and people Mutualism: some shrimp live on anemones and keep them clean in return for protection Maxillopoda Include barnacles in the subclass Thecostrae. These are mostly sessile crustaceans Feed by extending legs through calcareous plates to filter feed Barnacles are hermaphroditic Some lack gills (Branchiura Subclass) Ectoparasites of marine and freshwater fish Range from 5-10 mm long Video: https://www.youtube.com/watch?v=kAzMhI7SEN8 Endoparasites such as tongue worms Video: https://www.youtube.com/watch?v=ppE oQ9U8kQ8 Infect respiratory systems of vertebrates, mostly reptiles but occasionally mammals, and airsacs of birds Range from 1 to 13 cm in length Remipedia Genetic studies show they are the crustacean most closely related to insects and are most primitive form of crustacean Many even resemble many species of aquatic insect larvae Only 10 described species All known species are found in caves to the sea Have between 25 and 38 segments Ostracoda Often have short bodies and lack appendages Many species are parasitic Enclosed in a two-part carapace and look somewhat like a clam Typically around 1 mm but can be up to 30 mm in length Can be found on the sea floor or in freshwater habitats Also found in humid forest soils Video: https://www.youtube.com/watch?v=8xEMhwvNO5s Cephalocarida Only 12 described benthic species Live in coastal bottoms from intertidal zones to 300 m deep Lack eyes, a carapace, and abdominal appendages Hermaphrodites: Discharge eggs and sperm from same duct Referred to as horseshoe shrimp 2-4 mm long No fossil records found Video: https://www.youtube.com/watch?v=jwaUCwg3zx8 Branchiopoda Class characteristic is that they have legs, called phyllopodia, that serve as respiratory organs. These legs may be used for filter feeding and locomotion. Branchiopoda species are mostly freshwater species Branchiopoda (continued) Includes Order Anostraca (Fairy and brine shrimp), Order Notostraca (Tadpole shrimp (triops)), and Diplostraca (water fleas) About 800 species of brine shrimp alive today Video: https://www.youtube.com/watch?v=VmfN4l-MolI Video: https://www.youtube.com/watch?v=g-Uq2fl3duQ Anostraca – Do not have a carapace Notostraca – Carapace forms a large dorsal shield. Tadpole Shrimp are a living fossil, similar to horseshoe crabs, at close to 400 million years old, mostly unchanged for the past 250 million years Diplostraca – Carapace encloses entire body but not head. This includes the water flea and is the most diverse order of all the brachiopods Diplostraca - Water Fleas Water fleas have are over 600 different recognized species Present in almost all inland aquatic habitats but are rare in the oceans Most are only 0.2 to 6.0 mm long Have a single median compound eye Video: Daphnia Heart Beat: https://www.youtube. com/watch?v=M4wC q-yMj_w Water Fleas (continued) Mostly asexual but can reproduce sexually. During sexual reproduction, resting (dormant) eggs are produced which allow the species to survive harsh conditions such as cold and desiccation Males are only produced when unfavorable conditions arise Since they are planktonic and therefore the base of the food chain, they are frequently used as an indicator of toxic conditions, observed by whether or not they reproduce and/or survive a given aquatic environment. Video: Daphnia Heart Beat Explanation: https://www.youtube.com/watch?v=ibDwYghgb2k Video: Daphnia Babies: https://www.youtube.com/watch?v=b7UFjsAYr3Y Video of Lab Procedures: https://www.youtube.com/watch?v=HhOUwlOdxkA
