MARVELOUSMARiNEMAMMALS - by John Stewart

Sep 28, 2026

Uploaded by Kurz

A clear, educational overview of two marine mammals—manatees and sea otters—explains where they live, what they eat, and how their bodies are specially adapted for life in water. Manatees are described as gentle herbivores with split lips, continual back-teeth growth, and breathing valves for long underwater stays. Sea otters are presented as small, warm-blooded mammals with extremely dense fur and limited body fat, highlighting the survival importance of insulation.

LanguageEnglish

CategoryLiterature

FormatPDF

Pages20

Reading Time31 min

AccessFree to download

Manatees

Diet and feeding adaptations

Marching molars

Senses and breathing

Threats and extinction pressures

Sea Otters

Size and warmth

Dense fur for survival

MARVELOvSMARiNE.420MAMMALSby John Stewart用HOUGHTON MIFFLIN HARCOURT # MARVELOUSMARiNEMAMMALS byJohn Stewart 201 HOUGHTON MIFFLIN HARCOURT School Publishers PHOTOGRAPHY CREDITS:Cover,◎Chris HowesWild Places Photography/Alamy;p.2,Oblickwinkel/Alamy;p.3,OStephenFrink/CORBIS;p.4,The Image Bank/Cousteau Society/Getty Images;p.5,OGarry Gay/Alamy;p.6,OJeff Foott/DiscoveryChannel Images/Getty Images;p.7,OJeff Foott/Getty Images;p.8,OJon Sergison/Alamy;p.9,OKevin Schafer/Corbis;p.10OStuart Westmorland/Getty Images;p.11,ODanita Delimont/Alamy Images;p.12,ORoyalty-Free/Corbis;p.13,OAndyHolligan/Getty Images;p.14,OHarcourt Telescope. Copyright ◎by Houghton Miflin Harcourt Publishing Company All rights reserved.No part of this work may be reproduced or transmitted in any form or by any means,electronic ormechanical,including photocopying or recording,or byany information storage and retrieval system,without the priorwritten permission of the copyright owner unless such copying is expressly permitted by federal copyright law.Requestsor permission to make copies of any part of the work should be addressed to Houghton Mifflin Harcourt School Publishers,Attn:Permissions,6277 Sea Harbor Drive,Orlando,Florida 32887-6777. Printed in China ISBN-10:0-547-25310-9 ISBN-13:978-0-547-25310-7 23456780940181716151413121110 | f you have received these materials as examination copies free of charge,Houghton Mifflin Harcourt School Publishers
retains title to the materials and they may not be resold.Resale of examination copies is strictly prohibited. | | --- | | Possession of this publication in print format does not entitle users to convert this publication,or any portion of it,into
electronic format. | | --- | ~2 cd ( 5.1 / Motorboats like the one in this photograph can hurt a manateeor sea otter. Marvelous mammals dwell beneath the ocean'ssurface.However,human actions are threateningmembers of the large marine ecosystem such asmanatees and sea otters.What makes theseanimals special?Let's find out the answer tothis question. Manatees Manatees are mammals that spend their livesin the water.They can grow as long as 15 feet (4.6m).They can weigh as much as 3,500 pounds (1,588 kg).They eat plants.Sometimes they can beseen basking in the shallow freshwater of a river.However,manatees live in salt water as well. A manatee often feeds on floating vegetation.Short front flippers have claws to help grip plants.Manatees use their odd lips to move the plants intotheir mouths.Each lip is split in the middle.Thesides of each lip can move independently. Manatees are eating machines that can eat upto 150 pounds(68 kg)of plants each day.They spend a lot of time analyzing and nibbling plants atthe bottom of shallow waters.If the water is clearenough for you to see them,they might remindyou of grazing cattle.That's why manatees aresometimes called "sea cows."They are not relatedto cows,though.Their closest land cousin is theelephant. Lettuce looks good to a manatee! You can see the split upper lip in this photo. Manatees have a special trait that no otheranimal shares:"marching molars."Because theyspend so much time chewing their food,their frontmolars,or teeth,wear down quickly.No problem!Replacing them is not an ordeal.Their back teethon each side of the jaw are growing all the time.When a front molar gets too worn to work well,itfalls out—and the rest of the molars move forward,one by one,"marching"neatly into their newplace.A replacement molar begins to grow rightaway in the "hole"left in the back of the row. Manatees have big heads,but their eyes aresmall.They do not see very well underwater.Theirhearing is good,even though their ears look likemere pinholes.Because a manatee is a mammal,fresh air is vital for its survival.It breathes througha snout that sits high on its head.It just has to stickits nostrils out of the water to take a breath.Thesenostrils have valves to let air in—and to keep w

FAQs

What makes manatees special compared with other animals?

Manatees have “marching molars.” Their front teeth wear down as they chew, but replacement back teeth grow continuously and shift forward when a front molar falls out.

How do manatees breathe when they are underwater?

They breathe through a snout with nostrils that sit high on their head. The nostrils have valves that let air in and keep water out, and they typically come up for air about every five minutes.

Why do sea otters stay warm in the ocean?

Sea otters must keep warm without relying on large body fat. Instead, they have the densest fur in the world, with up to about a million hairs per square inch.

Sep 28, 2026

Uploaded by Kurz